Lawyers for the seven Pakistani students still held in prison on terrorism charges have announced they will launch a legal challenge against the UK government this week. Criminal charges against all the students were dropped in May because of insufficient evidence, but they have been kept locked in high-security prisons under immigration laws. Two lawsuits would contest the legality of the government's use of secret evidence in their continued imprisonment as well as the lawfulness of the initial arrest, The Independent reported. In total, 12 students were arrested in April, but five have already been freed.