ISLAMABAD/LAHORE: A day after the judges of the Islamabad High Court received letters allegedly laced with a toxic substance, similar letters arrived in the Supreme Court and the Lahore High Court, prompting the Counter-Terrorism Department to register two terrorism cases in Islamabad and Lahore. The letters in the top court were sent to CJP Qazi Faez Isa, Justice Athar Minallah, Justice Jamal …