Tiahrt had earned the highest rating, by "voting for every pro-gun bill." This included "critical pro-gun reforms" like the 2005 Protection of Lawful Commerce in Arms Act (PLCAA); "legislation to expand Right-to-Carry to national parks and wildlife refuges", the Tiahrt Amendment to reform the ATF, and "legislation to restore" Second Amendment rights to Washington, DC. The A+ ranking took into consideration the letter he submitted to court briefs that he signed as a "critical friend of the court briefs" in the 2008 landmark case District of Columbia v. Heller, in which the Supreme Court of the United States ruled that the Second Amendment protects an individual's right to possess a firearm unconnected with service in a militia for traditionally lawful purposes, such as self-defense within the home, and that Washington, D.C.'s handgun ban and requirement that lawfully-owned rifles and shotguns be kept "unloaded and disassembled or bound by a trigger lock" violated this guarantee. and the 2010 SC case McDonald v. Chicago which found that the right of an individual to "keep and bear arms" is protected by the Due Process Clause of the Fourteenth Amendment against the states, clearing up any uncertainty left in the wake of the Heller case.