SAN FRANCISCO — FedEx Corp. has taken its first swing at knocking out a federal criminal case alleging it shipped drugs for illegal Internet pharmacies.

FedEx’s lawyers at Arguedas, Cassman & Headley and Skadden, Arps, Slate, Meagher & Flom argued in a court filing Wednesday that in its role as a common carrier the company is shielded under federal law from the government’s claims. FedEx’s motion to dismiss also claims the government’s charges amount to a violation of the company’s Fifth Amendment right to fair warning that its conduct ran afoul of the law.