Appellate Advocacy Blog

Editor: Tessa L. Dysart
The University of Arizona
James E. Rogers College of Law

Wednesday, July 21, 2021

Legal Syllogisms, Part I

Justice Cardozo once said that as many as 9 out of 10 legal issues can be resolved by deduction alone.[1] The most useful form of legal deduction is the syllogism, which generally has two premises and a conclusion.[2]

Crack open any book on syllogisms and the author will lead with something like this: All men are mortal; Socrates is a man; thus, Socrates is mortal. This is a categorical syllogism, which is by far the most common in the law.[3] A categorical syllogism sets up a broad proposition (all/some/no X are Y), gives an example (all/some/no of group A are X), then concludes that what is universally true must be true in a particular instance of that universal (all/some/none of group A is X).[4] Convincingly using categorical syllogisms in legal analysis is a matter of hitting on the relevant aspects that characterize a class, then showing that your case does or does not fit in that class.  

Most appellate arguments and cases can be reduced to syllogisms. As an exercise, take any United States Supreme Court case and try to reduce it to three sentences—a general proposition, a few specific facts showing that this case fits within (or without) that class, then a conclusion that what is true of the class in general is true (or not) of this case.[5] Marbury v. Madison: the Constitution is supreme over laws passed under it; the Judiciary Act of 1789 conflicts with Article III of the Constitution by adding to the Supreme Court’s original jurisdiction; therefore, that part of the Judiciary Act conflicting with Article III is void. McCullough v. Maryland: The federal government is supreme over the state governments; if the states could tax the federal government, they would be supreme over it; therefore, the states cannot tax the federal government. Wickard v. Filburn: Congress has the power to regulate both interstate commerce and things affecting interstate commerce; growing one’s own wheat on a farm for personal consumption affects the interstate market for wheat; therefore, Congress can regulate growing one’s own food for personal consumption.    

Courts often reduce counsels’ arguments to syllogisms to zero in on points of disagreement. In Blasland, Bouck & Lee v. City of North Miami,[6] North Miami had sued a contractor (Blasland) that it had hired to clean up a Superfund site, believing that the cleanup did not meet federal standards. In a previous lawsuit involving the same site, it had gotten a favorable judgment against other defendants who had met federal standards in their cleanup efforts. The court later offset a judgment against Blasland with the prior judgment, reasoning that North Miami’s recovery would otherwise be duplicative. North Miami appealed, saying that the setoff was improper. The Eleventh Circuit broke down the City’s argument into a series of syllogisms—simplified here—to explain precisely where it believed that the City’s reasoning went awry: 1. Duplicative awards justifying an offset exist only if the recovery in the second suit was available in the first suit; 2. The claim against Blasland was not available in the first suit; 3. Therefore, the award against Blasland was not duplicative and it is not entitled to an offset.[7] The Court held that this argument was a “fine []syllogism, with flawlessly connected episyllogisms, but its initial premise is flawed. The flawed premise is that . . . duplication of awards only exists if what has been awarded in the present case rightfully could have been recovered in the prior litigation. That is not [the] law.”[8]

The best attorneys often use syllogisms to the same effect. To illustrate, I looked at briefs from prominent practitioners in the U.S. Supreme Court in 2019 and 2020. For example, Kannon Shanmugam of Paul, Weiss, used it in a petition for certiorari review in C.H. Robinson Worldwide, Inc. v. Miller, 20-1425 (with citations removed to aid readability):

What is more, the court of appeals badly misconstrued this Court's decision in American Trucking Associations, Inc. v. City of Los Angeles. The court's attenuated chain of reasoning went like this: In American Trucking Associations, the Court stated that the FAAAA's preemption provision “draws a rough line between a government's exercise of regulatory authority and its own contract-based participation in a market.” The FAAAA's preemption provision includes common-law claims. Thus, because Congress also used the term “regulatory authority” in the safety exception, it must also include common-law claims.

He then used that syllogistic framework to attack that reasoning:

That syllogism is multiply flawed. As a preliminary matter, the Court in American Trucking Associations was not interpreting the safety exception-indeed, its only mention of the safety exception was to deem it “not relevant here.” If anything, any hints from American Trucking Associations cut the other way. The governmental action at issue there was a core exercise of the “regulatory authority of a State”: the “Board of Harbor Commissioners” (an administrative agency) enforced a “municipal ordinance” (a positive-law enactment), the violation of which was “a violation of criminal law” (enforced by state or local officials). It is little wonder that the Court described the governmental action there as “regulatory authority.”

Two former members of my office—Tyler Green and Tera Peterson—used it to good effect in an amicus brief supporting Arizona in McKinney v. Arizona, 589 U.S. ____ (2020): 

McKinney's argument can be succinctly stated as this syllogism:

  • New rules (like Ring) apply to cases on direct review.
  • His case is again on direct review because the Arizona Supreme Court's actions after the Ninth Circuit's conditional grant of habeas relief reopened his twenty-year-final judgment.
  • Therefore, Ring's new rule applies to his case.

The minor premise in McKinney’s syllogism is invalid. So his conclusion is invalid too. The Arizona Supreme Court did not reopen his case—or transform his final sentence into a non-final one—by correcting a non-Ring error. Concluding otherwise would gut Teague’s finality framework, which protects the States’ criminal judgments from unwarranted federal intrusion. It would make those judgments perpetually subject to reopening: Every conditional habeas grant would force States to relitigate convictions under every new procedural rule decided since the original conviction became final.

Finally, Jeff Fisher of Stanford University included this in his winning brief in Ramos v. Louisiana, 590 U.S. ___ (2020) (again, with citations removed):

For decades, this Court has addressed questions like the one here by asking whether the Fourteenth Amendment's Due Process Clause “incorporates” the relevant protection of the Bill of Rights. Applying that test, a simple syllogism establishes that the Due Process Clause incorporates the Sixth Amendment's unanimity requirement against the states. First, the Court held long ago that the Jury Trial Clause applies to the states. The Clause is “fundamental to the American scheme of justice.” Second, “if a Bill of Rights protection is incorporated, there is no daylight between the federal and state conduct it prohibits or requires.” This Court first crystallized this concept in Malloy v. Hogan. . . .  The Court reiterated this concept in McDonald. . . . Just last Term, this Court reaffirmed this rule without a dissenting vote. . . . .This reasoning controls here.

I could go on. That’s just a sampling of prominent practitioners in the span of a single year. But it makes the point. The syllogism is a powerful tool that each attorney should use not just to think through cases, but to explain their and others’ reasoning.


[1] Judge Aldisert agrees. Aldisert, Logic for Law Students, 69 U. Pitt. L. Rev. at 2, 12.

[2] Syllogisms can be complex, with one conclusion becoming a premise in the next, as a stacked set leads (eventually) to the desired conclusion. These are called polysyllogisms and episyllogisms. More often, they are simplified by implying rather than spelling out one of the premises. These are called enthymemes. See, e.g., Fulton v. City of Philadelphia, (2021) (Gorsuch, J., concurring).

[3] Syllogisms can also be hypothetical or disjunctive. A hypothetical syllogism consists of at least one conditional (if-then) premise that necessarily leads to the conclusion (if X then Y; X; therefore, Y; or if X then Y, if Y then Z, therefore if X then Z). Id. at 34. And a disjunctive syllogism sets up two options (either X or Y), says which one attains (X), then concludes that the other is not (therefore, not Y). Patrick J. Hurley, A Concise Introduction to Logic 34 (10th ed. 2007).

[4] Id.; Aldisert, Logic for Law Students, 69 U. Pitt. L. Rev. at 4 (describing syllogistic logic as “[w]hat is true of the universal is true of the particular.”).

[5] Judge Aldisert advocates for this exercise and gives several examples. Logic for Law Students, 69 U. Pitt. L. Rev. at 4.

[6] 283 F.3d 1286 (11th Cir. 2002).

[7] Id. at 1295-96.

[8] Id. at 1296.

Appellate Advocacy, Appellate Practice, Legal Writing | Permalink


Post a comment