18 Pa.C.S. § 6122: Proof of license and exception.

(a) General rule.--When carrying a firearm concealed on or about one's person or in a vehicle, an individual licensed to carry a firearm shall, upon lawful demand of a law enforcement officer, produce the license for inspection. Failure to produce such license either at the time of arrest or at the preliminary hearing shall create a rebuttable presumption of nonlicensure.

(b) Exception.--An individual carrying a firearm on or about his person or in a vehicle and claiming an exception under section 6106(b) (relating to firearms not to be carried without a license) shall, upon lawful demand of a law enforcement officer, produce satisfactory evidence of qualification for exception.