Cause: Illegal activities by Nixon administration. Effect: Congressional investigations, Nixon's resignation, increased focus on government ethics.

Cause: Terrorist attacks on the U.S. Effect: Creation of Department of Homeland Security, increased security measures, wars in Afghanistan and Iraq.

Expanded health insurance coverage to millions, but faced political and legal challenges.

Declared state-sponsored segregation in public schools unconstitutional, overturning Plessy v. Ferguson.

Established a woman's constitutional right to an abortion, impacting state laws and sparking ongoing debate.