Express Scripts and several of its affiliated pharmacies filed a lawsuit on Thursday asking an Arkansas federal judge to overturn a state law set to go into effect next year that would ban pharmacy benefit managers from owning pharmacies.

One of the largest health care companies in the country is suing Arkansas over a new pharmacy law signed by Gov. Sarah Sanders in April.

CVS and Express Scripts are asking a federal judge to block an Arkansas law prohibiting pharmacy benefit managers from owning or operating pharmacies in the state