Most Important Constitutional Law Cases to Know

Con Law exams are rule-application exercises dressed as case knowledge. Your professor does not want you to recite the facts of Wickard v. Filburn; she wants you to spot that a federal statute regulates a local, non-commercial activity and then run the Lopez categories. So the cases worth memorizing are the ones that generate a usable test or a usable exception.

That means you should learn roughly forty cases in depth and be able to name another forty as illustrations. The forty core cases cluster into five buckets: judicial power and justiciability, federalism and congressional power, separation of powers, the Fourteenth Amendment (equal protection and substantive due process), and the First Amendment. The list below is the standard national core. Your syllabus may weight one bucket heavily and skip another entirely — some schools split Con Law into two courses and push the entire First Amendment into the second — so check your professor's coverage before you spend a week on speech cases you will not be tested on.

Marbury v. Madison, 5 U.S. (1 Cranch) 137 (1803), establishes judicial review and, less famously but more testably, holds that Congress cannot enlarge the Supreme Court's original jurisdiction beyond what Article III specifies. Martin v. Hunter's Lessee, 14 U.S. (1 Wheat.) 304 (1816), extends review to state court judgments on federal questions.

For justiciability, Lujan v. Defenders of Wildlife, 504 U.S. 555 (1992), gives you the three-element standing test: injury in fact that is concrete, particularized, and actual or imminent; causation; and redressability. Baker v. Carr, 369 U.S. 186 (1962), sets out the political question factors and holds legislative apportionment justiciable; Rucho v. Common Cause, 139 S. Ct. 2484 (2019), holds partisan gerrymandering claims are not. Learn Lujan's elements verbatim — standing is the single most commonly tested threshold issue.

McCulloch v. Maryland, 17 U.S. (4 Wheat.) 316 (1819), is the most important case in the course after Marbury. It gives you the Necessary and Proper Clause standard (the end must be legitimate and the means plainly adapted to it) and the principle that states cannot tax federal instrumentalities. Gibbons v. Ogden, 22 U.S. (9 Wheat.) 1 (1824), defines commerce broadly and establishes federal supremacy over conflicting state regulation.

The modern Commerce Clause line runs Wickard v. Filburn, 317 U.S. 111 (1942) (aggregation of local activity), through Heart of Atlanta Motel v. United States, 379 U.S. 241 (1964), and Katzenbach v. McClung, 379 U.S. 294 (1964) (civil rights legislation upheld under commerce power), to the modern limits. United States v. Lopez, 514 U.S. 549 (1995), supplies the three-category framework — channels, instrumentalities, and activities substantially affecting interstate commerce — and requires that the regulated activity be economic for aggregation to apply. United States v. Morrison, 529 U.S. 598 (2000), applies Lopez to strike the civil remedy in the Violence Against Women Act. Gonzales v. Raich, 545 U.S. 1 (2005), sustains federal regulation of homegrown marijuana as part of a comprehensive economic scheme. NFIB v. Sebelius, 567 U.S. 519 (2012), holds Congress cannot compel commerce but can tax inactivity, and that conditions on existing Medicaid funds were unconstitutionally coercive.

For the limits on federal power over states, know the anticommandeering trio: New York v. United States, 505 U.S. 144 (1992), Printz v. United States, 521 U.S. 898 (1997), and Murphy v. NCAA, 138 S. Ct. 1461 (2018). For spending, South Dakota v. Dole, 483 U.S. 203 (1987), gives the four-part conditional spending test. For Section 5 of the Fourteenth Amendment, City of Boerne v. Flores, 521 U.S. 507 (1997), imposes the congruence-and-proportionality requirement, and Shelby County v. Holder, 570 U.S. 529 (2013), applies equal sovereignty to the Voting Rights Act coverage formula.

Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579 (1952), is the framework case, and what you actually cite is Justice Jackson's concurrence and its three zones of presidential authority. Every executive power question on an exam should open with a Youngstown zone classification.

United States v. Nixon, 418 U.S. 683 (1974), recognizes a qualified executive privilege that yields to a demonstrated need in a criminal proceeding. INS v. Chadha, 462 U.S. 919 (1983), invalidates the legislative veto and gives you bicameralism and presentment. Morrison v. Olson, 487 U.S. 654 (1988), upholds removal restrictions on an inferior officer; Seila Law LLC v. CFPB, 140 S. Ct. 2183 (2020), narrows removal protection for single-director agencies. Trump v. United States (2024) recognizes absolute immunity for a President's core constitutional acts and presumptive immunity for other official acts — expect it on any exam written after 2024.

Start with the state action requirement: the Civil Rights Cases, 109 U.S. 3 (1883), and Shelley v. Kraemer, 334 U.S. 1 (1948). Then United States v. Carolene Products Co., 304 U.S. 144 (1938), footnote four, which is the theoretical source of tiered scrutiny.

Equal protection: Brown v. Board of Education, 347 U.S. 483 (1954); Loving v. Virginia, 388 U.S. 1 (1967) (strict scrutiny for racial classifications, including antimiscegenation laws); Washington v. Davis, 426 U.S. 229 (1976) (discriminatory purpose, not disparate impact alone, triggers strict scrutiny); Craig v. Boren, 429 U.S. 190 (1976) (intermediate scrutiny for sex); United States v. Virginia, 518 U.S. 515 (1996) (exceedingly persuasive justification); Students for Fair Admissions v. President & Fellows of Harvard College, 600 U.S. 181 (2023) (race-conscious admissions fail strict scrutiny); Romer v. Evans, 517 U.S. 620 (1996) (rational basis with bite).

Substantive due process: Lochner v. New York, 198 U.S. 45 (1905), and its repudiation in West Coast Hotel Co. v. Parrish, 300 U.S. 379 (1937), and Williamson v. Lee Optical Co., 348 U.S. 483 (1955). Then Griswold v. Connecticut, 381 U.S. 479 (1965); Washington v. Glucksberg, 521 U.S. 702 (1997) (deeply rooted in history and tradition, plus careful description of the asserted right); Lawrence v. Texas, 539 U.S. 558 (2003); Obergefell v. Hodges, 576 U.S. 644 (2015); and Dobbs v. Jackson Women's Health Organization, 597 U.S. 215 (2022), which overrules Roe and Casey and installs Glucksberg as the governing method.

Content discrimination is the organizing concept. Reed v. Town of Gilbert, 576 U.S. 155 (2015), holds that a law content-based on its face gets strict scrutiny regardless of benign motive. R.A.V. v. City of St. Paul, 505 U.S. 377 (1992), bars content discrimination even within unprotected categories.

For unprotected and low-value speech: Brandenburg v. Ohio, 395 U.S. 444 (1969) (incitement requires direction to imminent lawless action and likelihood of producing it), which supersedes Schenck v. United States, 249 U.S. 47 (1919); New York Times Co. v. Sullivan, 376 U.S. 254 (1964) (actual malice for public officials); Miller v. California, 413 U.S. 15 (1973) (obscenity); Central Hudson Gas & Electric Corp. v. Public Service Commission, 447 U.S. 557 (1980) (commercial speech). Add Texas v. Johnson, 491 U.S. 397 (1989), for symbolic speech and Tinker v. Des Moines Independent Community School District, 393 U.S. 503 (1969), for students.

Religion clauses: Employment Division v. Smith, 494 U.S. 872 (1990) (neutral, generally applicable laws need no free exercise exemption), and Church of the Lukumi Babalu Aye v. City of Hialeah, 508 U.S. 520 (1993) (laws targeting religion get strict scrutiny). For establishment, Kennedy v. Bremerton School District, 597 U.S. 507 (2022), replaces the Lemon v. Kurtzman, 403 U.S. 602 (1971), test with a history-and-tradition inquiry — do not write Lemon as governing law.

Build a one-page chart per doctrinal area with four columns: case name, the trigger fact, the rule, and the case that limits it. The trigger fact column is what makes this work on an exam — when the fact pattern says 'homegrown wheat,' you should reflexively write Wickard, then immediately ask whether Lopez's economic-activity requirement changes the answer.

Memorize the tests, not the opinions. You will lose points for failing to state that intermediate scrutiny requires an important government interest and substantial relation; you will lose nothing for forgetting that Craig v. Boren involved 3.2% beer. Cite cases as shorthand for rules: 'Under Lopez, the activity must be economic for aggregation.' That single sentence does more work than a paragraph of facts.

Finally, track overrulings. Dobbs displaced Roe and Casey, Kennedy displaced Lemon, SFFA displaced Grutter v. Bollinger, 539 U.S. 306 (2003), and Trump v. Hawaii, 585 U.S. 667 (2018), stated that Korematsu v. United States, 323 U.S. 214 (1944), was gravely wrong the day it was decided. Casebooks lag behind. If your edition is more than two years old, verify the current state of any rule before you rely on it.