A constitutional crisis has been described as a situation that a legal system's constitution or other basic principles of operation appear unable to resolve; it often results in a breakdown in the orderly operation of government.
- The Stamp Act of 1765
- The Nullification Crisis of 1832.
- In 1841 the death of President William Harrison resulted in Vice-President John Tyler becoming President, the first vice-president to succeed thus to the presidency. Since resolved by Constitutional Amendment.
- American Civil War.
- 1876 presidential election leading to the Compromise of 1876. Democrats disputed the electoral votes in three states. Democrats agreed to the election of Rutherford B. Hayes provided that he would end Reconstruction. This was the beginning of the Democrats reign of terror in the American South and of segregation and Jim Crow.
- Watergate. Watergate era produced several major reforms dealing with abuse-of-power, such as the War Powers Act, requiring Congressional authorization for military action; the Fair Campaign Practices Act, which created the FEC and required stricter reporting and accountability for campaign contributions; and the Freedom of Information Act, which mandates disclosure and open access to government officials' records and documents.
- The election of Hillary Rodham Clinton, first US president elected under criminal investigation.
- Speculation that a Republican senate will block all Supreme Court nominees by Hillary Clinton if she is elected President.
- The possibility that a legal dispute over the 2016 election (like Bush v. Gore in 2000) will result in a 4-4 tie at the Supreme Court.