Legislation approved Thursday in the Michigan Senate would ban the manufacturing, assembling, selling, purchasing, importing and possessing of firearms or firearm parts that don’t have a valid serial number.

The U.S. Supreme Court is expected to weigh in on regulations on 3D-printed firearms after several states have filed lawsuits regarding their regulation.

The Maine Gun Safety Coalition is asking state lawmakers to ban ghost guns after an untraceable firearm was used by the alleged UnitedHealthcare CEO shooter. Firearms known as “ghost guns” do not have a serial number as they are usually constructed at home with a kit or with the assembly of separate pieces.