Mountain States Legal Foundation (MSLF) is an American 501(c)(3) nonprofit[2] conservative free market public interest law firm based in Lakewood, Colorado.

[7][8] MSLF was incorporated in Denver, Colorado, in 1976 with funding from the National Legal Center for the Public Interest and Joseph Coors.

[citation needed] In 1995, its president, William Perry Pendley, argued before the Supreme Court in Adarand Constructors, Inc. v. Peña, the case in which the justices ruled that preferential treatment based on race is almost always unconstitutional.

In a case dismissed in 2002, MSLF sued George W. Bush for failing to overturn a designation of national monuments action by Bill Clinton.

[16] MSLF's sources of funding have included Texaco, U.S. Steel, Phillips Petroleum, and ExxonMobil corporations, and Castle Rock Foundation.