Legal analysis: 1. Applicable premise: infringement is established. 2. Subjective elements: The seller has subjective goodwill. 3. Objective requirements: the infringing product has a legal source.

Legal basis: "Regulations on the Implementation of the Trademark Law of the People's Republic of China" Article 79 The following circumstances are circumstances that can be proved to have obtained the goods legally according to Article 60 of the Trademark Law: (1) There is a supply list and payment receipt legally signed and stamped by the supplier, which have been verified to be true or recognized by the supplier; (2) There is a purchase contract signed by both the supplier and the seller, and it has been verified that it has been truly fulfilled; (3) There is Legal purchase invoices and the items recorded on the invoices correspond to the goods involved; (4) Other circumstances that can prove the legal acquisition of the goods involved.