For the U.S. Department of Justice’s top lawyers, an unusual deal to get rid of a legal headache from Minnesota two years ago has turned into a major political headache in Washington today.

In 2011, the Justice Department wanted the city of St. Paul to drop its appeal to the U.S. Supreme Court in an unrelated case that threatened the "disparate impact" theory, the agency’s favored way to enforce fair housing cases. In exchange, the Justice Department agreed not to intervene in an unrelated whistleblower case against St. Paul, wounding the lawsuit’s chances of succeeding.