Commerce Clause (Article I, Section 8, Clause 3):

• Explanation: Grants Congress the power to regulate trade and commerce among the states, with foreign nations, and with Native American tribes. It has been a basis for significant federal government power expansion, especially in cases involving economic activities.

Necessary and Proper Clause (Article I, Section 8, Clause 18):

• Explanation: Also known as the "Elastic Clause," it allows Congress to make laws that are necessary and proper for executing its enumerated powers. This clause has been used to justify the expansion of federal power beyond explicitly stated powers in the Constitution.

Supremacy Clause (Article VI, Clause 2):

• Explanation: Establishes that the Constitution, federal laws, and treaties are the "supreme law of the land," meaning that state laws that conflict with federal law are invalid. This clause plays a crucial role in federalism cases.

Establishment Clause (First Amendment):

• Explanation: Prohibits the government from establishing an official religion or unduly favoring one religion over another. It is often cited in cases involving the separation of church and state.

Free Exercise Clause (First Amendment):

• Explanation: Protects individuals' rights to practice their religion freely, without government interference. This clause is often involved in cases where religious practices conflict with government policies.

Equal Protection Clause (14th Amendment, Section 1):

• Explanation: Requires states to provide equal protection under the law to all people within their jurisdictions. This clause is central to cases involving discrimination and civil rights.

Due Process Clause (5th and 14th Amendments):

• Explanation: Prohibits the government from depriving individuals of life, liberty, or property without due process of law. The 5th Amendment applies to the federal government, while the 14th Amendment extends this protection to the states. It is crucial in cases involving fundamental rights.

Privileges and Immunities Clause (14th Amendment, Section 1):

• Explanation: Prevents states from discriminating against citizens of other states in favor of their own residents. This clause is less frequently cited but is important in cases involving interstate travel and economic activity.

Full Faith and Credit Clause (Article IV, Section 1):

• Explanation: Requires states to recognize the public acts, records, and judicial proceedings of other states. It is important in cases involving marriage, divorce, and custody across state lines.