When the 1990 English docudrama Who Bombed Birmingham? cast serious doubt on the guilt of six men convicted of bombing two British pubs in 1974, Prime Minister Margaret Thatcher declared that a "television program alters nothing." But, as Alan Rosenthal concludes, Thatcher was wrong. The film engendered a new inquiry that led to the release of the convicted men.

Rosenthal notes that docudrama wields more influence than the average documentary and that "reality-based stories taken from topical journalism are the most popular drama genre on U.S. and British television today." This...