The Supreme Court today will hear arguments in American Trucking Associations’ case against aspects of the Port of Los Angeles’ Clean Trucks Program.

The oral argument will be the culminating moment in a case that has been working its way through the courts for more than four years. A ruling is expected in July.

At issue are provisions of the multi-layered concession program for drayage carriers that the port put together in order to reduce engine emissions in the area.

While a lower court upheld ATA’s claim that the port could not compel independent drivers to become employees of drayage companies, it also found that the port’s off-street parking and placarding requirements are not pre-empted by another law.

ATA is contesting this finding, and another one concerning the port’s ability to prevent federally licensed carriers from entering its grounds.

The U.S. Justice Department is joining ATA in the matter. 

Related Story: Supreme Court to Hear Challenge of LA Ports' Clean Trucks Program