The Huthi armed group, which since late 2014 has controlled large parts of Yemen, has – in conjunction with forces loyal to former President Ali Abdullah Saleh and state security and intelligence agencies – carried out hundreds of arbitrary arrests and detentions of its opponents, as well as enforced disappearances, torture and other ill-treatment of detainees. The clampdown intensified dramatically after the start of the Saudi Arabia-led coalition’s military campaign in March 2015. Through the examination of 60 individual cases in Sana’a, Ibb, Ta’iz and Hodeidah between December 2014 and March 2016, this report reveals how the Huthi forces have swept up political opposition figures, activists and journalists from their homes, work places, meetings or protests, as part of a broad crackdown against those who have opposed their take-over of government institutions. Eighteen individuals whose cases are featured in this report are still being held. Some have been held for as long as 17 months, without being charged or brought before a court. Even official release orders from prosecuting authorities in the capital Sana’a have failed to secure detainees’ releases. Amnesty International is calling on Huthi armed group and state institutions across Yemen to stop carrying out arbitrary arrests and enforced disappearances of political opponents, and to release those detained in such circumstances.