In the democratic system of government in the United States, each person—rich, poor, or middle class—is entitled to one vote. Ideally, government officials are supposed to pass and enforce laws for the benefit of the whole community, without favoring one constituent over another. Unfortunately, politicians’ currying favors for constituents in return for cash or other inducements is what lies at the heart of many political scandals.

Two examples from American history illustrate this classic form of political corruption. Warren G. Harding, president of the United States from 1921 to 1923, appointed friends to government positions who then used their position to benefit people in return for cash. His secretary of the interior, Albert Fall, took $400,000 in gifts and loans from oil millionaires Edward Doheny and Harry Sinclair while at the the same time leasing...