Port Protection Act of 2003

Port Protection Act of 2003 - Directs the Secretary of Homeland Security to require the inspection, contents verification, and sealing by personnel of the Department of Homeland Security, at ports or airports outside the United States, of any cargo containers destined for the United States. States that the Customs Service shall not allow the entry of any noncontainerized cargo by any means other than a vessel or airplane until it has verified that it does not contain a chemical, biological, or nuclear weapon.

Directs the Commandant of the Coast Guard to inspect, at least 200 miles from the United States, any cargo vessel carrying cargo destined for the United States and verify that it does not have a chemical, biological, or nuclear weapon.

Requires the Secretary to deny entry into the United States to cargo vessels that: (1) are carrying cargo not in compliance with this Act; or (2) are not inspected by the Commandant of the Coast Guard in accordance with this Act or that fail such an inspection.