What is the ruling on working in a commission of judicial ombudsmen that seeks to aid the oppressed in reclaiming their rights, yet is compelled to serve criminal summonses to which the rulings of Sharia are not applied?

As long as the purpose of the body is to support the oppressed and restore their rights, and there is no defiance of the rulings of Islamic law, then the fundamental principle is the permissibility of working in it. If, however, some details of its work involve something forbidden, then the prohibition applies only to that specific action, and not to the work as a whole.