The International Religious Freedom Act of 1998 (Public Law 105–292, as amended by Public Law 106–55, Public Law 106–113, Public Law 107–228, Public Law 108–332, and Public Law 108–458) was passed to promote religious freedom as a foreign policy of the United States, to promote greater religious freedom in countries which engage in or tolerate violations of religious freedom, and to advocate on the behalf of individuals persecuted for their religious beliefs and activities in foreign countries. The Act was signed into law by President Bill Clinton on October 27, 1998.
This is the legal mechanism that lets citizens engage the US on IRF issues.

Read International Religious Freedom Act