Legal Language and N-Grams at SCOTUS

Words have meaning. The context, tone, and interplay give rise to nuances that is the basis for statutory and case law interpretation. But sometimes the iteration of words have meaning too. The frequency and repetitiveness of certain words can at times given insight into a culture or society.

At Jurix: The 24th International Conference on Legal Knowledge and Information Systems in Vienna, Austria earlier this week, Daniel Martin Katz, Michael J. Bommarito II, Julie Seaman, Adam Candeub & Eugene Agichtei proposed the idea of Legal N-Grams in conjunction with a beta pre-release of Legal Language Explorer, a new web interface that graphs every decision of the United States Supreme Court between 1791 and 2005.

They explain the concept of n-grams in their paper,

While well known to linguistics scholars for some time, the concept of n-grams has recently been popularized by the release of the Google N-gram explorer. A byproduct of the Google Books Library Project, the n-gram explorer allows end users to use language as a prism to explore institutional and cultural transformation processes.

Simon Fodden raised the issue of n-grams here on Slaw back in 2009.

The authors envision legal researchers looking at the origin of a phrase and its subsequent usage by providing quick aggregate insights of temporal importance. Social and political scientists will also be able to look at terminology within broader legal philosophies, doctrines and paradigms,

Judges who create dominant common law rules often use words in new and novel ways. Distinctive language and verbal formulae are the raw materials by which judges help establish their reputation as intellectual thought leaders…

This is especially true in common law systems where the strength and importance of a legal rule often correlates with its pervasiveness in opinions and its persistence through time.

The Legal Language Explorer might be useful for a variety of different applications. Consider, for example, the following query that I inputed:

Of course the term “black” can arise in a wide variety of different contexts that have absolutely nothing to do with racism, which is what could be described as “noise,” there is a small increase where Jim Crowe laws were enacted, followed by a more substantial increase in the interwar era which precedes a very sharp increase during the Civil Rights era up to the modern day. Although the term “African-American” doesn’t substantially plot at all, the more contentious term “Negro” can be noticeably observed even after it fell into disuse in academic and socially acceptable discourse.

Here’s the plot of some of the legal n-grams related to doctrines of statutory interpretation:

Although it appears as if “legislative intent” has always been discussed at SCOTUS, it has been featured far more prominently in recent years, especially from the 70’s to the mid-90’s. Though the term “original intent” also mirrors the trend of the term “legislative intent,” the term “originalism” only pops up once, in Missouri v. Jenkins (1995). Even in this case it’s not used to explicitly refer to the doctrine of originalism aside from citing a law review article using the term in its title, which again demonstrates the limitations of using this software to make general assumptions. Although the concepts can be found over the years in case law, an explicit reference may suggest a greater acceptance or familiarity with the concept. Similarly, the search for “living constitution” only provides three results, two of which are also references to titles of law review articles during the 60’s and 70’s. It’s only in Rummel v. Estelle (1980) that the court expressly uses “living constitution” to refer to a dynamic application of constitutional interpretation,


It is also true that this Court has not heretofore invalidated a mandatory life sentence under the Eighth Amendment. Yet our precedents establish that the duty to review the disproportionality of sentences extends to noncapital cases. Supra, at 289-293. The reach of the Eighth Amendment cannot be restricted only to those claims previously adjudicated under the Cruel and Unusual Punishments Clause. “Time works changes, brings into existence new conditions and purposes. Therefore a principle to be vital must be capable of wider application than the mischief which gave it birth. This is particularly true of constitutions. They are not ephemeral enactments, designed to meet passing occasions. They are, to use the words of Chief Justice Marshall, `designed to approach immortality as nearly as human institutions can approach it.'” Weems v. United States, 217 U.S., at 373 .

We are construing a living Constitution. The sentence imposed upon the petitioner would be viewed as grossly unjust by virtually every layman and lawyer…

[emphasis added]

The authors intend to expand the database to include Court of Appeal and other court decisions, and has tools to modify graph format and export data. You can read more about the tool on the blog post here.

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