In United States law, providing material support for terrorism is a crime prohibited by the USA PATRIOT Act and codified in title 18 of the United States Code, sections 2339A and 2339B. It applies primarily to groups designated as terrorists by the State Department. The four types of support described are "training," "expert advice or assistance," "service," and "personnel."
In June 2010, the United States Supreme Court upheld the law in an as-applied challenge in the case Holder v. Humanitarian Law Project, but also left open the door for other as-applied challenges.[1] The defendants in the case had sought to help the Kurdistan Workers' Party in Turkey and the Liberation Tigers of Tamil Eelam learn means of peacefully resolving conflicts.[2][3]