Is it permissible to work as a real estate and land expert for municipal courts that rule by man-made laws?

The work of an expert in lands and real estate is originally permissible, but it may become forbidden if he submits his reports for a judge to rule by his man-made law, because that is considered cooperation in sin and aggression. Allah Almighty has forbidden that by saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression" [Al-Ma'idah: 2]. Therefore, the questioner should look for another job.