In the US, anyone refusing to cooperate with a Grand Jury can be held in jail with a civic, “non-criminal” charge for the duration of the Grand Jury (usually 18 months). In practice, the US uses the Grand Juries as a form of “political internment” to punish activists for their opposition to US government policies and practices. In 1981 a Federal Grand Jury was convened in the Eastern District of New York, to investigate activities of the Fuerzas Armadas Liberation Nacional. Five activists were subpoenaed, including Ricardo Romero, a leader in the MLN Mexicano and Maria Cueto the Director of the National Commission on Hispanic Affairs of the Episcopal Church. Ricardo had also been jailed in 1977 for several months for refusing to testify to a Grand Jury investigating the Puerto Rico independence movement.. All five refused to testify or even appear at the Grand Jury. The subpoenas were withdrawn after substantial protest by the Episcopal Church and the Puerto Rican and Mexicano communities.
Sites: https://peopleslawoffice.com/improper-use-of-federal-grand-jury-michael-deutsch-political-repression/.