As is the case with most free trade agreements, importers simply claim preferential tariff eligibility at the time of import. This claim can later be subject to verification by the customs administration in view of determining if it was valid. Proving preferential tariff entitlement requires assembling and presenting relevant facts and documents that support the claim. But just how much evidence is necessary in order to discharge that burden? In Canada there has always been a disconnect between what the Canada Border Services Agency (CBSA) deems necessary in the course of an origin verification and what the courts find satisfactory in the course of a judicial review. What follows are certain illustrations of that disconnect and how it usually gets resolved by Canadian courts.