Constitutional Law
Judicial power and justiciability
Standing requires injury in fact, causation, and redressability; generalized grievances and most taxpayer suits fail. Ripeness, mootness (with exceptions for capable-of-repetition and voluntary cessation), and the political question doctrine screen the rest. Congress cannot confer standing on a plaintiff who lacks it.
Federalism limits
Congress may reach channels of interstate commerce, instrumentalities, and activities substantially affecting interstate commerce (Wickard aggregation). The Dormant Commerce Clause invalidates discriminatory state laws absent a legitimate local purpose that cannot be served otherwise; nondiscriminatory burdens are weighed under Pike. Spending conditions must relate to the federal interest and must not be coercive. The Tenth Amendment bars commandeering of state legislatures and executives. Preemption turns on congressional intent.
Individual rights
The Fourteenth Amendment requires state action; the Thirteenth does not. Procedural due process protects fair process; substantive due process applies strict scrutiny to fundamental liberties. Equal protection tiers: race, national origin, and fundamental rights get strict scrutiny; sex and illegitimacy get intermediate; everything else gets rational basis. Incorporation applies most Bill of Rights provisions to the states.
Worked example
A state bans all new highway signage within 500 feet of a road except official government signs. The ban is content- and speaker-based, so strict scrutiny applies; the government-speech exception does not save the general ban's viewpoint preference.
Rule of thumb: name the tier before arguing outcome, and always ask who the actor is - no state action, no Fourteenth Amendment claim.