On the Evolution of Inferential Practices in Late Modern English and Present-Day English Court Opinions

2.1. Inferential Evidential Markers

Inferential evidential markers have been analyzed in relation to epistemic modality (e.g., Altshuler & Michaelis 2020; Miecznikowski & Jacquin 2023; Ricciardi, Ryskin & Gibson 2023), as regards specific expressions (e.g., Mortelmans 2012; Fetzer 2014a; Aijmer 2026) and across discourse types (e.g., Buysse 2010; Reber 2012; González, Roseano, Borràs-Comes & Prieto 2017). Inferentials are characterized by ambiguous semantics in that the source of information indicated by inferentials may be “based on visible or tangible evidence, or result” (Aikhenvald 2004:63) and there might be fuzzy boundaries between evidential expressions of “inference” and “sensory perception” (Bednarek 2006:fn11).

2.2. Linking Adverbials

Linking adverbials represent a linguistic structure often deployed to evoke the discourse relations of result and inference. According to Biber, Johansson, Leech, Conrad, and Finegan (2021:869), “[l]inking adverbials in the result/inference category [e.g., therefore, consequently, thus, as a result, hence, in consequence] show that the second unit of discourse states the result or consequence – either logical or practical – of the preceding discourse.” Lenker (2010) offers the most comprehensive and authoritative source on the evolution of linking adverbials—or what she calls connectors—in the history of English to date. Having emerged during Early Middle English and classified as a lexicalized connector, therefore represents a highly frequent linking adverbial with rather opaque “resultive” semantics (Lenker 2010:79, 96-97). Her study excludes “fully transparent, i.e. non-lexicalized phrases” such as for . . . the reasons (Lenker 2010:10) or the clausal constructions that is why, this is why, and that’s why, which are characterized as “overt signals” (Lenker 2010:22).

Linking adverbials are highly constrained by style and/or genre. While Present-Day English adverbial connectors tend to be positioned in initial and medial position in written prose, spoken English is characterized by clause-initial adverbial connectors, with sentence-medial adverbial connectors being only marginal (Lenker 2010). So represents the most frequent linking adverbial in conversation (together with then; Lenker 2010:45) and is probably the most widely studied (Raymond 2004; Buysse 2010; Reber 2012; González, Roseano, Borràs-Comes & Prieto 2017; Koops & Lehmann 2022). The variation between the three near-synonymous adverbials therefore, hence, and thus has even been explained by idiosyncratic style differences (Biber, Johansson, Leech, Conrad & Finegan 2021:881). Then, so, and therefore have been found to be typical of Late Modern English science texts, a genre characterized by “argumentation, exemplification and drawing conclusions” (Grund & Smitterberg 2014:176). These findings are corroborated by past research on evidential markers more generally, which has shown that these are tightly connected to speaker stance and can be reflexive of speakers’ tacit considerations of ‘entitlement,’ ‘responsibility,’ or ‘authority’ over the knowledge displayed (Du Bois 1986; Fox 2001:176).

2.3. Court Opinions

The court opinions of the U.S. American Supreme Court have attracted considerable attention from various analytic angles. Court opinions represent a legal and, more importantly, legally binding text type in which the judge communicates their decision to a multilayered audience. To take American district courts as a case in point, the opinions are addressed to “the litigants, other courts, the public, and, ultimately, to the corresponding Court of Appeals, i.e., the reviewing court” (Hinkle, Martin, Shaub & Tiller 2012:410). Court opinions are characterized by intertextuality: in terms of content and final verdict, they are, for instance, related to the briefs by the counsels (Long & Christensen 2008; Hazelton, Hinkle & Spriggs 2019). Due to their communicative function, it is not only important what judges write but also how they write court opinions. Here clarity (i.e., comprehensibility), vagueness, and stance-taking have been identified as stylistic factors. To begin with clarity, the overall clarity with which court opinions are written, does not depend on the political ideology, but may depend on the idiosyncratic style of the authoring justice. Generally, majority opinions show more complexity, that is, are less understandable, than dissents (Owens & Wedeking 2011). Vagueness in expression, achieved by hedging and intensifiers, might be due to the textual function which a specific section of the court opinion may serve. Such vagueness may also depend on the status of a court within the hierarchy of the legal system and its potential audience (Hinkle, Martin, Shaub & Tiller 2012). Stance markers in court opinions of the Supreme Court of the United States serve to construct the identity and authority of the court and its justices as well as to convey a coherent and shared value and believe system (Szczyrbak 2014:117). Adverbials expressing attitude and emphasis to strengthen the argumentation represent a typical feature of court opinions of U.S. state and federal supreme courts (Finegan & Lee 2010; see also Mazzi 2010).

The literature demonstrates that linking adverbials represent conventional stance markers to express inferential evidential meaning in discourse, ranging from older, more lexicalized and opaque forms to more recent and transparent structures. Their usage patterns in court opinions, where stance markers serve to strengthen the argument of the court and to contribute to the normative construction of identity and authority of the judges, are thus likely to be subject to change, especially in recent times, when conceptualization of roles and subsequently discourse preferences have been shown to undergo changes in the course of democratization (see e.g., Reber 2021; Kranich, Bruns & Sabra 2025; Kranich & Knewitz 2025).

4.1. The Development of Inferential Adverbials in the Corpus of US Supreme Court Opinions Between the 1790s and 2010s

The use of inferential adverbs in court opinions can be observed since the 1790s, when they were authored under the first chief justice of the United States, John Jay (Supreme Court Historical Society n.d.). The search for the common English inferential linking adverbs therefore, hence, and consequently (Biber, Johansson, Leech, Conrad & Finegan 2021) revealed a preference for therefore (raw frequency 74,231/574 pmw) compared to hence (9458/73) and consequently (7349/57). ¹ While therefore dominates across all periods in the corpus, the data shows its overall decline over time (Figure 1).

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Figure 1.

Relative Frequencies of therefore, hence, and consequently in the Corpus of US Supreme Court Opinions Between the 1790s and 2010s (pmw)

The steady decline of therefore is paralleled by consequently but at a lower level. During the 1790s, consequently starts out as the more popular choice than hence but after a drop in use during the 1890s, it lags behind hence. The evolution of hence is less straightforward, remaining on a relatively low level. Biber, Johansson, Leech, Conrad, and Finegan (2021:878-879) corroborates this finding: therefore is listed among the most frequent linking adverbials in English, being most commonly found in academic discourse.

There are fewer prepositional phrases than adverbs expressing inferential stance in the corpus. A search for the variants of for . . . reasons(s) . . . shows a relatively low frequency (for . . . reasons: raw frequency 7297/56 pmw; for . . . reason: 3636/30). These adverbials are attested throughout the entire span of the corpus (Figure 2).

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Figure 2.

Relative Frequencies of the Inferential Propositional Phrases for . . . reasons . . . and for . . . reason . . . in the Corpus of US Supreme Court Opinions (1790s-2010s; pmw)

With respect to for . . . reasons . . ., the corpus reveals an interesting general increase from around the 1930s to the 2010s. This plural form is associated with a greater referential scope than its singular alternative. Due to its relative dominance in the corpus, it will be investigated in more detail in Section 4.3. Nevertheless, the frequencies of the prepositional phrases remain clearly behind the ones of the adverb therefore. Note, however, that the temporary rise of for . . . reasons . . . and for . . . reason . . . stands in stark contrast to the steady decline of the most common inferential linking adverbs therefore in the corpus.

Compared to the adverb and prepositional phrases, the frequencies of the clausal constructions that is why, this is why, and that’s why are marginal in the corpus. In terms of raw and normalized frequencies pmw, that is why dominates (129/3), followed by the variant this is why (52/0) and the contracted form that’s why (18/0; Figure 3).

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Figure 3.

Relative Frequencies of the Inferential Clausal Constructions that is why, this is why, and that’s why in the Corpus of US Supreme Court Opinions (1790s-2010s; pmw)

The form that is why can be first observed in the early twentieth century. First instances of this is why and that’s why are deployed during the mid-twentieth century. The evolution of the variant that is why is noticeable, peaking in its frequency during the 2000s. Again, Biber, Johansson, Leech, Conrad, and Finegan (2021:876) serve as a first reference to interpret the results. They state that linking adverbials of formats other than adverbs and prepositional phrases are more common in academic prose than in conversation where they seem to be almost absent. Yet this does not explain the changes in use evident in court opinions, and the contracted form is clearly a marker of conversational style. To gain a better understanding of these changes in frequency, the usage of therefore, for . . . reasons . . ., and that is why/that’s why needs to be teased apart in more detail, especially as to how these constructions are functional for evidential stance-taking in the corpus.

4.2. Therefore

Strikingly, the linking adverbial therefore most commonly collocates with another inferential stance-marker, the cognitive verb conclude in the court opinions. Three of the following four most common expressions with a higher raw frequency than 300 instances represent terminology typical of “legal language” (Tiersma 2000). These comprise the speech act verbs reverse and affirm as well as the adjective void, all of which represent some of the jargon used in the disposition of the court opinion. ² An exception is the more general verb pray which enjoys an interesting frequency. A closer look at the constructions reveals consistent syntactic patterns. The collocations of conclude, reverse, and affirm almost exclusively occur in constructions with first-person subjects and show the highest distribution between the 1940s and 2010. By contrast, collocations of void and pray are typically used in formats with third-person subjects and are abandoned in the early twentieth century (see Figures 4 and 5). The various preferences for cooccurrence with different grammatical persons can reveal differences in the typical discursive functions.

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Figure 4.

Collocations of therefore with a conclude, affirm, and reverse in the Corpus of US Supreme Court Opinions (1790s-2010s; pmw)

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Figure 5.

Collocations of therefore with void and pray in the Corpus of US Supreme Court Opinions (1790s-2010s; pmw)

Beginning with the verb conclude, let us investigate each of these constructions to discuss the implications of these collocation patterns. The use of conclude with therefore (raw 902/7 pmw) can be observed throughout the entire span of the corpus, but peaks during the mid- and late twentieth century. There is a strong preference for first-person plural subjects, that is, claims of collective discursive identity, over first-person singular subjects which convey an individual discursive identity. Excerpt 4 exemplifies a typical use of conclude with a first-person plural subject during the 1970s and 1980s where the frequency of the verb peaks. The example shows the semi-fixed construction We therefore conclude that X. In addition, the corpus contains variants such as We conclude therefore that X, and, less often, Therefore we conclude that X, We must therefore conclude that X.

The example is taken from the main opinion which represents the vote of the majority of the court. The construction We therefore conclude that X frames what follows as a position which is based on inferences drawn from the previous sentence. The use of the linking adverbial makes this evidential relation between the assertions in the two sentences explicit, constructing the evidential authority of the voting majority of the court. At the same time, it functions as a wide-discourse-level discourse marker to mark the start of the conclusion, that is, signposting the decision as a result of all the foregoing.

According to the Oxford English Dictionary, the meaning of reverse, classified as a transitive verb, can be described as follows: “To revoke or annul (a legal decision, esp. one made by a lower court or authority).” The collocation with reverse (raw 410/3 pmw) is first attested during the 1810s and is most frequent between the mid-twentieth century and the beginning of the twenty-first century. Again, it is most commonly used with first-person plural subjects. During the 1970s and 1980s, where the verb is found most often, it is typically used in the semi-fixed construction we therefore reverse (X). ³ Consider Excerpt 5 taken from the main opinion:

The inferential adverbial frames the decision as based on the prior line of argument, lending evidential authority to the declaration backed by the court majority. Infrequent variants of the construction are we are therefore constrained to reverse X and we therefore decline to reverse.

Constructions with the verb affirm become most frequent as of the mid-twentieth century in the corpus. The manually checked analysis of the two dominant decades during which this usage is found (the 1970s and 1980s), suggests a preference for first-person singular subjects. A recurrent format is I would therefore affirm X. Fewer variants of this format include I therefore would affirm X and Therefore, I would affirm X. Strikingly, affirm always collocates with would in first-person uses, which seems to follow legal style conventions (Federal Judicial Center 2013). At the same time, the modal verb signals irrealis meaning, which is appropriate given that the dissenting opinion does not gain legal force.

In contrast to first-person plural subjects, the singular form indexes the voice of an individual justice, concurring in and/or dissenting from the main opinion. Consider Excerpt 6 for a typical example:

Indexed by the first-person singular pronoun I, this format is not used in the main opinion which usually presents the majority opinion of the court but in a concurring or—in this case—a dissenting opinion. The disposition of the dissenting justice is presented as an inference based on his prior reasoning and judgment. Compare this to Excerpt 7, which illustrates the corresponding construction with a plural subject (we therefore affirm X).

Signaled by the inferential adverb therefore, the affirmatory verdict of the court is framed as being derived from the prior line of reasoning summed up in the previous sentence. Grounded in the collective voice of the voting majority of justices, the lack of modal qualification constructs the verdict as legally binding. This is also corroborated by the subsequent sentence (It is so ordered).

In a legal context, the adjective void means “Having no legal force; not binding in law; legally null, invalid, or ineffectual” (OED). Collocations of therefore with void are most frequently found until the 1880s and marked by third-person subjects. Excerpt 8, taken from a dissenting opinion, illustrates a typical case.

The example begins with an assertion about the prohibition of corporations from purchasing real estate under certain circumstances. In the subsequent sentence, the linking adverbial therefore contextualizes the assessment of such purchases as being void, that is, not legally binding, as an inference from this assertion.

The verb pray is generally used in what are now archaic transitive constructions, meaning “To ask (a person) earnestly for something, to beseech” or “To ask earnestly, beseech (God, a person, etc.) to do something, or that something may be done” (OED). Excerpt 9 is a typical example taken from a disposition quoted in the court opinion.

Here the petitioner’s request for permission to resign from his office is presented as a consequence of the medical issues established in the first sentence. This discourse relation is made explicit by the use of the inferential adverbial therefore.

The adverb therefore expresses the discourse relation of result/inference between the prior sentence or stretch of discourse and the sentence in which therefore is used. The evidential marker serves to make resultative/inferential meaning explicit, which is implicitly indexed by the positioning within the discursive context of the disposition (where the final verdict is expected) and may be co-constructed by evidential expressions (the verb conclude). The collocations reveal an interesting pattern: following collocations of third-person subjects (void and pray), which cease to be used by the turn of the nineteenth and twentieth century, collocations of therefore tied to the deictic center of the collective court or individual judges (conclude, reverse, and affirm) become frequent during the mid-twentieth century. Here, various dimensions of change seem to become visible: the drop of pray stands for a more general linguistic change. A brief search reveals a general decline of void and rise of conclude, reverse, and affirm in the corpus, which suggests stylistic changes in this legal genre. The concurrent shift from third-person to first-person constructions points to increasing communicative immediacy (Koch & Oesterreicher 1985, 2007, 2012) in this local context.

4.3. For (. . .) The Reasons (. . .)

The prepositional phrase for (. . .) the reasons (. . .) is more versatile and specific in use than the linking adverbial therefore and the clausal constructions that is why/that’s why. The phrase may be forward-looking, that is, it may project the basis on which a result/inference is formed, pointing to the reason for the writer’s position. Consider Excerpt 10 for a typical example.

Similar to the adverb and the clausal constructions, the prepositional phrase may also be backward-looking, indexing what follows to be the result of/inference from the prior stretches of discourse. Excerpt 11 shows a typical example.

The phrasal expression may also be more specific and concrete than the adverb and the clausal constructions and may not be linking in a proper sense. This is exemplified by Excerpts 12 and 13:

The prepositional phrase For the reasons identified in Briscoe, supra, at 342-344 makes reference to a previous court opinion to point to the inferential basis on which the writer’s assertion is based. This also shows that such backward-looking constructions may create “intertextuality” (Bhatia 1998; Steel 1998; Witt, Huggins, Governatori & Buckley 2024) common to legal verdicts to authenticate and substantiate the claim made.

Establishing an intratextual relation (Steel 1998; Witt, Huggins, Governatori & Buckley 2024), the dissenting justice references the main opinion (and substantially for the reasons it gives) to construct the evidential basis of his position (I do not think this statute is unconstitutionally vague). Excerpt 14 illustrates that for (. . .) the reasons (. . .) constructions may be used in coordination with other prepositional phrases.

Here, the two coordinated phrases (For the reasons we have stated, and upon the authorities we have cited) serve as an evidential basis, substantiating, and authorizing the following disposition of the court (the judgments of both courts must be reversed). Note that the semantics of the modal must are potentially fuzzy, a usage which can often be observed in the depositions in the data. Its use conveys “epistemic necessity” since the future legal action is inferred from the prior reasoning as well as “deontic obligation,” imposing an obligation on the recipient courts (Leech, Hundt, Mair & Smith 2009:87).

Let us now turn to the typical collocations in which the inferential prepositional phrase engages. For comparison with the analysis of therefore, the focus is on the five most frequent collocations. The construction for (. . .) the reasons (. . .) shows a recurrent use in conjunction with verbs typical of the legal language of court opinions: reverse (raw 351/3 pmw), affirm (raw 343/3 pmw), and dissent (raw 292/2 pmw) as well as with the epistemic verbs hold (raw 311/2 pmw) and think (raw 243/2 pmw).

Similar to the cognitive collocate of therefore and conclude, the near-synonyms hold and think show a preference for first-person subjects in the corpus (Figure 6). To begin with a more detailed discussion of hold, we can observe a frequent use of the verb with a plural first-person subject between the 1890s to the 2010s (raw 226/2 pmw), while singular first-person subjects are more limited in time (from the 1960s to the 2010s) and number (raw 36/0 pmw). Excerpt 15 presents a typical case.

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Figure 6.

Collocations of for . . . the reasons with hold and think in the Corpus of US Supreme Court Opinions (1790s-2010s; pmw)

The example is taken from the main opinion, which represents the opinion of the majority vote of the court. The collective pronoun we thus indexes the court as the authoritative source of the opinion presented. The verb think behaves in similar ways: it shows a continuous use from the 1890s to the 2010s, typically with a plural first-person subject (raw 156/1 pmw; singular first-person subject: raw 63/1 pmw). Like we hold (Excerpt 15), the chunk we think can be implemented to contextualize an assertion as the authoritative opinion of the court’s majority. Alternatively, this chunk can be found in minority opinion. This is exemplified in Excerpt 16, taken from a dissenting opinion from the 1940s during which we think was particularly common.

The reference to a prior court opinion (For the reasons stated in Kuehner v. Irving Trust Co., 299 U.S. 445, 57 S.Ct. 298,) lends evidential authority to the subsequent position (we think that if Congress had provided . . .). The epistemic matrix clause we think frames the assertion in the subsequent that-clause as the individual position of the dissenting justices. Contrary to the findings with respect to therefore (Section 4.2), the verbs reverse and affirm tend to take third-person subjects when used together with for . . . the reasons . . .. (Figure 7).

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Figure 7.

Collocations of for . . . the reasons . . . with reverse and affirm in the Corpus of US Supreme Court Opinions (1790s-2010s; pmw)

Reverse can be observed in passive constructions with a third-person subject throughout almost the entire span of the corpus, that is, between the 1810s and 2010s. The collocation first occurs with a first-person subject (and in active form) relatively late, that is, during the 1960s, and then shows a continuous use on a relatively low level until the 2010s. Excerpt 17 is a common case of the passive use of reverse with a third-person subject.

The verb is used in the disposition of the court opinion and occurs in a typical collocation with the verb remand. The prepositional phrase for the reasons stated provides the evidential grounding of the legal action ordered by the court (the judgment of the Court of Appeals for the Second Circuit is reversed, and the case is remanded for further proceedings consistent with this opinion). Over the span of the 1840s to the 2010s, a continuous occurrence of the verb affirm with a third-person subject both in active and passive constructions can be observed. Like reverse, affirm first occurs with a first-person subject only during the 1960s. Excerpt 18 demonstrates the passive form of affirm which in an exemplary case from the 1900s when the collocation spiked in frequency.

The excerpt represents the disposition of the court opinion. The prepositional phrase For the reasons already stated provides the verdict the judgment of the Circuit Court of Appeals is affirmed with evidential authority. The meaning of the verb dissent is “To think differently, disagree, differ from, in (an opinion), from” (OED). The collocations of dissent show an interesting development (Figure 8).

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Figure 8.

Collocations of for . . . the reasons . . . with dissent in the Corpus of US Supreme Court Opinions (1790s-2010s; pmw)

In total, there is clear preference for constructions with a third-person subject (raw 171/1 pmw) over these with a first-person subject (raw 120/1 pmw). Between the 1940s and 1960s, dissent with a third-person subject rises considerably before declining until 1980s and finally being abandoned. By contrast, forms with a first-person subject show a continuous use between the 1950s and 2010s. Excerpt 19 illustrates a typical example of the verb dissent with a third-person subject.

Constructions with third-person subjects are generally used by dissenting justices to claim their disagreement with the majority opinion. Here, the subject explicitly references the two dissenting justices who have not joined the majority vote. Constructions with a first-person subject, which is generally a singular pronoun (raw 118), are generally also deployed by dissenting justices to claim their disagreement with the majority opinion. A common routine found in the corpus includes the adverb respectfully as exemplified in Excerpt 20.

Using the previous discourse in the minority opinion as an evidential basis, the justice closes with a declaration of dissent. Note that the adverb respectfully has been treated as a “marker of disrespect” in legal discourse (Wright, Robson, Murray-Edwards & Braber 2022:3, italics in the original). The emergence of third-person formats with explicitly named individual justices and of first-person constructions, which index the individual voice of the authoring justice, might suggest a “distinction” of single justices, that is, an increased focus “on the identity relation of differentiation” (Bucholtz & Hall 2005:600) since the 1940s.

The analysis of for . . . the reasons . . . has demonstrated a greater deictic flexibility of the prepositional phrase than that of the adverb therefore. The phrase can be used as a resource to indicate specific and concrete anaphoric and cataphoric relations, as well as to create “referential intertextuality” (Devitt 1991) and quote other legal sources. The most common collocations include the epistemic verbs hold and think with constructions involving a plural first-person subject indexing the voice of the majority vote (or a collective minority) first attested during the 1890s. Similarly, the collocations of the speech act verbs reverse and affirm serve to declare a collective decision, showing a preference of (passive) third-person constructions used in the disposition since the mid-nineteenth century. This is in stark contrast to the collocational patterns with therefore, which suggests a highly formulaic style of the genre and needs to be explored by future research. By contrast, the collocation of dissent represents an innovation from the mid-twentieth century, marking a noticeable voicing of distinctive disagreement in the court opinions.

4.4. That Is Why and That’s Why

The clausal construction that is why is used as an inferential marker across all portions of the court opinions. Both full and contracted forms can be observed in excerpts of court transcripts. Noticeably, the clausal construction is always positioned in a clause-initial (That is why all are appealable to the Courts of Appeals) or near-clause-initial slot (and that is why we oppose it). The subject of the subsequent clause is most often a first-person pronoun. Plural first-person pronouns tend to be used with verbs of communication or cognition. Consider Excerpts 21 and 22:

In his dissenting opinion, the justice first makes an assertion (Yet registration, like licensing, may have aspects of harassment and burden.). Using the clausal construction That is why, he frames the subsequent quotation as an account to corroborate his assertion (cf. Couper-Kuhlen 2007). Using the plural first-person pronoun we, he self-identifies as part of the in-group (“us”) and marks the subsequent paragraph as a quotation. The verb of communication (said) and reference to a previous court opinion at the Supreme Court of the United States (in Thomas v. Collins, supra, 540) contextualize what follows next as a quotation.

Excerpt 22, taken from the main opinion, begins with an assertion (“Reasonableness” standards are not foreign to sentencing law) which is backed up by a reference to statistics (Together, these cases account for about 16.7% of sentencing appeals). In what follows, the position of the court is presented. It is framed as an inference made from the previous line of argument (That is why we think it fair to assume). Inferential stance-taking represents a resource to claim and maintain evidential authority, specifically in argumentative contexts. Excerpt 23 shows the case of a first-person singular pronoun in subject position.

In this dissenting opinion, the justice presents his epistemic stance toward future court hearings (In future preliminary hearings, competent counsel can be expected to make sure. . .). He then delivers his assessment of the main opinion. The use of the inferential That is why frames the assessment as being based on the previous line of argument. In line with this, the first-person pronoun I and the epistemic verb think contextualize the assessment as the justice’s subjective position. In terms of another type of discourse in the public arena, Fetzer (2014b:73) has argued that I think in political discourse is a resource to frame chunks of speech as ‘subjectively qualified information.’ The examples suggest that that is why can function as an inferential marker in contexts where subjective, personal positions are presented. This is further corroborated by the observation that that is why may be used together with the stance adverbs perhaps, presumably, and indeed. Consider Excerpt 24:

In this excerpt, taken from the main opinion, first, an assessment is made (A statute [. . .] can be easily interpreted [. . .]). The epistemic adverbial perhaps hedges the subsequent inference as the epistemic stance of the author (Perhaps that is why the Oxford English Dictionary defines [. . .]).

The few instances of the contracted form that’s why are exclusively found in direct quotations of oral transcripts of past court proceedings which are referenced in the court opinion. The excerpts quoted from these transcripts are treated as relevant to the decision-making in the case at hand and may be presented as part of the main opinion or dissenting opinions to support the justice’s argument. Prosecutors and defendants are among the parties whose speech is quoted. This suggests that the contracted form represents conceptually spoken language use. Consider Excerpt 25 to illustrate this.

Here, the prosecutor addresses the jury in a murder trial, using that’s why to frame the rights and scope of decision-making of the jury as a consequence of the prosecuting attorney’s prior actions. Excerpt 26 exemplifies the use of that’s why in a story told in the confession by one of the defendants which is relevant to the decision of the case argued at the Supreme Court of the United States:

That’s why is used by the defendant to stage an event in the story formatted in non-standard grammar (we had went upstairs) as a consequence of and being motivated by the epistemic stance of the second defendant in the court trial (Kareem had thought she had more money).

The qualitative analysis has shown that that is why can be found in all components of the court opinions. There is a slight preference for first-person pronouns in collocating subjects. That is why may cluster with epistemic adverbs which hedge (perhaps, presumably) or boost (indeed) the evidential semantics of the clausal construction, as well as collocate with evidential verbs (e.g., say) or epistemic verbs (e.g., think), but the data does not contain clear enough patterns to be shown in collocation diagrams. Unlike therefore and for . . . the reasons, this clausal construction also occurs in transcribed speech of courtroom proceedings reproduced in the court opinions. The contracted form that’s why is exclusively found in direct quotations of oral transcripts. This suggests that the uses of that is why, and even more so, that’s why, index an increasing aspect of “conceptual orality” (Koch & Oesterreicher 1985, 2007, 2012) in the court opinions since the mid-twentieth century.