As of September 2015, it is not illegal to wear the patch of an outlaw motorcycle club. However, the federal government has specifically targeted wearing of the Mongol Nation logo in a series of court cases.
The Mongols trademarked their logo in 2005. A plea deal after a series of arrests in 2008 led to ownership of the trademark changing hands to the federal government, in theory allowing law enforcement officers to seize any clothing with the patch on it. The injunction was later partially lifted, but the government has re-opened their claim of ownership in court as of June 2015.