The U.S. Supreme Court on Monday reined in a Securities and Exchange Commission enforcement tool that the commission wanted to use to exact billions in fines for long-ago fraudulent acts.

A unanimous court ruled in Kokesh v. United States that the commission's “disgorgement” orders imposed on fraudsters amounted to a penalty and as such, must meet a five-year statute of limitations.

“This limitations period applies here if SEC disgorgement qualifies as either a fine, penalty, or forfeiture,” Justice Sonia Sotomayor wrote for the court. “We hold that SEC disgorgement constitutes a penalty.”