Litigators live in fear of citing bad law in their briefs. And with good reason: citing bad law is a quick way to lose credibility with the court and potentially jeopardize the outcome of an entire case. Case citators like Lexis’s Shepard’s and Westlaw’s KeyCite were invented to help attorneys avoid relying on bad law, but an excellent case citator should do more than simply flag overturned precedent.

I sat down with Pablo Arredondo, Casetext co-founder and Chief Product Officer, to discuss the release of Casetext’s citator, SmartCite^TM. SmartCite not only helps attorneys avoid the nightmare of relying on bad law but also helps attorneys understand how cases have cited other cases and discover good law that can be used to support specific legal arguments.

Q: Why are case citators so important?

A: Case citators were originally intended to alert attorneys to bad law. The very first case citator was invented by an attorney who was humiliated after citing bad law in a brief. In 1807, long before Shepard’s, KeyCite, or any citation system existed, an attorney named Simon Greenleaf relied in open court on a decision that had been overruled. His humiliation turned into inspiration to create the first citation index called A Collection of Cases Overruled, Doubted, or Limited in Their Application Cases in 1821. Whenever Greenleaf came across a case that had been negatively treated, he added a case to that list. Because it was written in the early 1800s, this list contains some strange jargon—for example, he referred to some cases as being “shaken” by other cases. But Greenleaf’s list was the first ever case citator and is credited with influencing the citators you see today.

Over time, case citators have evolved from  just a list of cases that have been reversed to a much more complicated analysis of how cases have been treated and cited by other cases.

Q: What is SmartCite?

A: SmartCite is Casetext’s advanced citator system. It is a collection of features designed to help attorneys assess whether an opinion is good law and to find other relevant cases citing that opinion. It has two overarching objectives: (1) to alert you to bad law, and (2) to alert you to other cases that you should read before deciding whether to rely on a case.

Q: What motivated Casetext to develop SmartCite?

A: You can’t research effectively if you don’t know whether the cases you’re reading are good law. But we wanted to go beyond a basic case citator that simply labels cases as overruled or not overruled. I knew we could use technology to make our case citator more intuitive and effective. Casetext uses cutting-edge technology to identify key patterns in the law. Those patterns enable us to determine how cases have been treated on appeal and how cases have been characterized by other cases.

Q: How was SmartCite developed?

A: SmartCite was developed through a combination of cutting-edge machine learning, natural language processing, and experienced editorial review. Let’s start with the technology.

SmartCite looks for patterns in millions of cases and uses judges’ own words to determine whether a case is good law and how a case has been cited by other cases. There are three key data sources analyzed by SmartCite. First, SmartCite looks at “explanatory parentheticals.” You know how judges will summarize other cases using parentheses? By looking for these phrases in opinions, we were able to extract 4.3 million case summaries and explanations written by judges! These explanatory parentheticals provide what I call “artisanal citator entries”: they are insightful, reliable, judge-written summaries of cases.

The second key data source leveraged by SmartCite are phrases in judicial opinions that indicate that a case has been negatively treated. For example, when a judicial decision cites to a case that is bad law, the judge will often explain why that case is bad law by saying “overruled by” or “reversed by” or “superseded by statute, as stated in…” The same is true with good law. Judicial opinions will often indicate that a case is “affirmed by” another case.

The third data source we use are Bluebook signals that judges use to characterize and distinguish cases. Bluebook signals can actually tell us a lot about a case. For example, when a judge introduces a case using “but see” or “cf.” or “contra,” the judge is indicating that this case is contrary authority, or that it has treated a legal issue differently from other cases. These contrary signals are powerful indicators of tension in the case law.

However, using algorithms to harvest judicial phrases and Bluebook signals is only the starting point of SmartCite’s analysis. We also rely on experienced editors to manage that process, review the case law, and make decisions on the “edge cases.”

Q: I’m seeing red, orange, yellow, and green flags on Casetext. What do these flags mean?

A: Let’s take each in turn.

• A red flag means that a case has been overruled or reversed on appeal. It indicates the most severe negative treatment.
• A green flag indicates that a case has been affirmed on appeal, which is positive treatment.
• A yellow flag indicates that you should proceed with caution because a case has been cited in another opinion with a contrary signal, like “but see” or “cf.” or “contra.” In other words, a yellow-flagged case has been cited in another case as creating a tension in the case law.
• An orange flag indicates that a case relies heavily on a negatively-treated case. An orange-flagged case has not itself been explicitly overruled, but because it relies heavily on a case that has been overruled, there is a risk that the orange-flagged case may no longer be good law.

Q: Other than the flags, what does SmartCite offer to help attorneys cite-check cases?

A: We offer a lot more than colorful flags! First, CARA A.I. is a powerful way to find relevant precedent. When you upload a brief or other legal document to CARA, CARA will return a list of cases that match the factual and legal context of the document. Each case in your CARA search results has a “citing cases” tab, where you can see the list of subsequent cases citing the case you’re reading. CARA will rank the list of citing cases according to the factual and legal context of your document. So, for example, if you look up the list of all cases that have cited Terry v. Ohio, 392 U.S. 1 (1968) following a CARA search, CARA will rank those citing cases so that the case that cites Terry v. Ohio that is most pertinent to the legal issues in your document is at the very top of the results.

If you reach Terry v. Ohio’s Citing Cases from a CARA search, the list of citing cases will be re-ranked to bring cases with fact patterns similar to your matter—the cases you most want to read—to the top.

We also offer a number of advanced filters to enable you to quickly search through and sort all cases that cite to a case. So for example, if you want to see all cases citing Terry v. Ohio, 392 U.S. 1 (1968) that involve a motion for summary judgment, you can apply our motion filter to limit the citing cases to that type of motion.

In addition, we offer a feature called “key passages” that allows you to see all the cases that have cited a specific portion of an opinion. For example, if you want to see all cases that have cited a particular paragraph of Terry v. Ohio, you can click on that paragraph and then search through and filter all cases that have cited that paragraph. When you read a case on Casetext, the “key passages”—the portions of cases that have been frequently cited by other cases—are highlighted in green. It is a great way to do an in-depth analysis of a specific portion of an opinion.

Also, if a sentence or phrase in a case has been emphasized by other cases, we will alert you to that fact using our “emphasis cite” tool. Every time a portion of a case has been quoted with emphasis added by another case, we will alert you to that fact by indicating the emphasized language in pink highlighting. You can then click on the pink highlighting to get a list of all cases that have emphasized that language, and you can also search through and filter those cases according to your chosen jurisdiction, motion type, party type, cause of action, and date range.

Another great tool we offer is our “similar issues” tool. If you find a paragraph in a case that matches your legal research issue and want to find other cases addressing similar issues, you can select that paragraph, and our “similar issues” tool will turn that paragraph into a natural language search, which will search the millions of cases in our database for similar language. In just a few seconds, you will get a list of all cases discussing legal issues that are similar to the paragraph you selected. While our “key passages” tool will give you a list of all cases that expressly cited to a specific paragraph in a case, our “similar issues” tool will give you a list of all cases addressing similar legal issues as a paragraph you selected, even if there is no direct citation relationship.

Finally, you can cite-check the authorities in your brief or other legal document using CARA. To cite-check a brief, just upload your legal document to CARA and click on the “cited in” tab. CARA will then generate a list of all the authorities in your document, with hyperlinks to each case, and will use red flags to alert you to any bad law in your document.

Q: How does SmartCite stack up to Lexis’s Shepard’s and Westlaw’s KeyCite?

A: We strive to be as close to perfect as possible with SmartCite, but attorneys should know that no citator is 100% accurate. This is true with SmartCite, as well as the citation systems offered by our competitors. Interestingly, a 2018 study published in the Law Library Journal by Paul Hellyer found that Westlaw’s KeyCite and Lexis’ Shepard’s often contradict each other. KeyCite and Shepard’s are well-respected citators, but this study shows that they are not infallible. So, my advice to practitioners is to use SmartCite (and any other case citator) as a starting point but not the ending point of their analysis. Like all tools, overreliance on a citator can be dangerous.  Even the smartest of citators cannot substitute for an attorney’s careful review and judgment.

To learn more about using Casetext’s SmartCite citation system, click here.