What are 5 things Congress cannot do?

What the phrase congressional powers means and why limits matter

The term congressional powers refers to the lawmaking authority granted to the U.S. Congress by the Constitution, including specific enumerated powers and the procedural limits that govern how Congress acts. The Constitution frames both what Congress may do and what it may not do, and readers benefit from separating the positive grants of power from the prohibitions placed elsewhere in the founding text. The Constitution

Enumerated powers are those the Constitution assigns directly to Congress, such as taxing, regulating interstate commerce, and declaring war. Other sections of the Constitution impose express limits, and the separation of powers means that those limits protect individual rights and preserve the roles of the executive and judicial branches. This arrangement matters because it shapes which subjects Congress can regulate and which actions are constitutionally off-limits. See analysis at Cornell Law School

Five concrete things Congress cannot do under the Constitution

Below are five core prohibitions grounded in constitutional text and established case law. Each item is followed by a brief reference to the controlling text or a key decision.

1. Make laws that abridge freedom of speech, religion, the press, assembly, or petition, as barred by the First Amendment. The Bill of Rights

2. Pass bills of attainder, which single out individuals or groups for punishment without trial. Article I, Section 9

3. Enact ex post facto laws that criminalize conduct retroactively or increase punishment after the fact. Article I, Section 9

4. Suspend the writ of habeas corpus except in cases of rebellion or invasion, a limitation that courts have treated seriously in modern practice. Boumediene v. Bush

5. Grant titles of nobility, a prohibition found in the Constitution that prevents the federal government from creating formal hereditary honors tied to rank. The Constitution

Courts enforce these prohibitions through judicial review, and where Congress or federal agents push constitutional boundaries, the judiciary may invalidate statutes or practices that violate these bars.

Courts interpret both parts when disputes arise, and readers should consult the text and judicial opinions for primary guidance. You can also read the Constitution online.

How the First Amendment limits Congress

The First Amendment bars Congress from making laws that abridge the freedoms of speech, religion, the press, assembly, and petition. This set of protections appears in the Bill of Rights and is a direct constraint on federal legislation. The Bill of Rights

These protections mean Congress cannot pass a law that, for example, broadly bans a particular religion or imposes prior restraint on the press; courts examine such statutes and may invalidate them if they impose unjustified limits on protected activity. Judicial review tests whether a challenged law meaningfully burdens a constitutional freedom and whether the government can justify that burden.

In practical terms, courts distinguish content-based limits from neutral regulations that incidentally affect expression, and they apply different levels of review depending on the right at issue and the nature of the law. The First Amendment’s text provides the central baseline that guides those judicial standards.

Article I, Section 9 limits: bills of attainder, ex post facto laws, and habeas corpus

Article I, Section 9 contains explicit prohibitions that restrict congressional action in several concrete ways: Congress may not pass bills of attainder or ex post facto laws, and it may not suspend the writ of habeas corpus except when rebellion or invasion makes suspension necessary. The constitutional text sets these limits. Article I, Section 9

Bills of attainder are laws that single out persons or easily identifiable groups for punishment without a judicial trial; the ban reflects a constitutional choice to reserve adjudication and punishment to the courts. Ex post facto bans prevent Congress from retroactively creating crimes or increasing penalties after the fact. Both prohibitions are textual and have long been read as safeguards of liberty and fair process.

The suspension clause limits the circumstances under which habeas corpus may be suspended, and modern cases have clarified how courts treat detention and habeas rights in national security contexts. Those cases show that habeas protections continue to matter in contemporary disputes over detention and the reach of federal authority. Boumediene v. Bush

Judicial review and how courts enforce limits on Congress

The power of federal courts to review and, if necessary, invalidate congressional statutes that conflict with the Constitution traces to Marbury v. Madison, which established judicial review as a central feature of the constitutional system. That decision positions courts as the arbiter of whether a law complies with constitutional text and structure. Marbury v. Madison

When a statute is challenged, plaintiffs bring suit in federal court and can seek relief if the law infringes a protected right or exceeds an enumerated power. A court that finds a constitutional violation may declare a statute unconstitutional and unenforceable, at least as applied to the parties before it. This process, repeated through appeals, is how constitutional limits on Congress are practically enforced in the U.S. legal system.

Doctrinal developments continue over time: later cases and statutory litigation refine how courts apply Marbury’s principle, and outcomes depend on the constitutional text, precedent, and the specifics of each dispute.

Limits created by the enumeration of powers and key Commerce Clause cases

The Constitution grants specific powers to Congress, an idea known as the doctrine of enumerated powers, and powers not conferred remain with the states or the people. The text of Article I and related clauses lays out this framework and shapes the questions courts ask when reviewing federal statutes. The Constitution See our powers of Congress explainer and a CRS report on federalism-based limitations at Congress.gov.

The practical lesson is that Congress has significant authority in areas tied to the enumerated powers, but those powers are not unlimited. Courts look for a sufficient constitutional basis for federal statutes, and where that basis is thin, judicial decisions can narrow federal reach.

Common misconceptions about what Congress can and cannot do

One common confusion is the difference between what Congress may do directly and what it can encourage indirectly. For example, Congress often uses the spending power and conditional grants to influence state policy, which is not the same as directly exercising an unspecified federal power. This distinction helps explain why some national aims are pursued through funding rather than direct regulation.

Another misconception is treating slogans or campaign promises as constitutional claims. Whether a proposed law is constitutional depends on its text and the controlling case law; courts, not slogans or political statements, determine whether a statute violates constitutional limits. Judicial interpretation can change the practical scope of congressional action over time, so legal outcomes may evolve.

Readers evaluating claims about congressional authority should consult primary sources and case summaries rather than rely on brief summaries or social media explanations. The Constitution and major decisions remain the authoritative starting points for determining what Congress can and cannot do. For broader context, see our constitutional rights hub.

Practical scenarios: how the prohibitions work in everyday disputes

Hypothetical 1: A proposed federal law that bans a specific religious practice nationwide would likely raise a First Amendment issue because the Constitution forbids Congress from making laws that abridge freedom of religion. Courts would examine whether the law targets religious exercise and whether any government interest justifies such a burden. The Bill of Rights

Hypothetical 2: A statute that retroactively criminalizes past conduct by imposing new penalties would run into the constitutional ban on ex post facto laws. That provision prevents Congress from passing laws that change legal consequences after the fact and is grounded in Article I, Section 9. Article I, Section 9

Hypothetical 3: A federal proposal to create hereditary titles or noble ranks would conflict with the Constitution’s prohibition on granting titles of nobility and would raise separation-of-powers and republican-government concerns anchored in the founding text. The Constitution

For readers interested in verifying how these constitutional bars apply in real disputes, the primary sources to consult are the Constitution itself and the relevant Supreme Court opinions, which provide the authoritative wording and reasoning courts use when resolving challenges to statutes.

How to evaluate claims that a proposed law exceeds congressional power

Use this short checklist when assessing whether a law might violate constitutional limits: identify the specific constitutional clause implicated; find controlling precedent that addresses similar facts; and consider whether courts have applied the clause in a comparable way. Those three steps help separate strong constitutional arguments from weaker ones.

Authoritative records to consult include the National Archives for the Constitution text and reliable case summaries on sites that provide full opinions and context. Looking at the reasoning of prior decisions is essential because courts rely on precedent to interpret constitutional provisions in new cases. The Constitution

A final caution: if a claim rests on a slogan or a single out-of-context sentence, seek the underlying statute and the controlling opinions before drawing firm conclusions about constitutionality. That approach keeps analysis anchored to primary materials and documented precedent.

Key takeaways and where to read more

The five core prohibitions discussed here are drawn directly from the Constitution and reinforced by judicial decisions: First Amendment protections against abridgment, bans on bills of attainder and ex post facto laws, the limited suspension of habeas corpus, and the ban on titles of nobility. Courts enforce these limits through judicial review.

For further reading, consult the Constitution text and the cited Supreme Court decisions for full opinions and historical context. Those primary sources are the best place to verify specific claims about congressional powers and constitutional limits. Marbury v. Madison