The U.S. Postal Service is delivering a new package to the federal courts — lawsuits.

Twice this year, disputes between the Postal Service and the commission that regulates it have landed in the U.S. Court of Appeals for the D.C. Circuit. In the latest case, filed on Oct. 22, postal officials want the D.C. Circuit to overturn a decision by regulators to reject an increase on the cost of mailing a letter or package.