Communication and consultation: First, try to actively communicate and negotiate with the patentee. Explain clearly the reason and purpose you need to prove, and seek the understanding and cooperation of the patentee. Sometimes, only through effective communication can the two sides reach an agreement.
Consult laws and regulations: learn local laws and regulations and understand the requirements and procedures for certification documents in the patent law. There may be relevant regulations stipulating that the patentee is obliged to provide supporting documents.
Seek legal aid: If communication fails, you can seek legal aid. Please consult a professional intellectual property lawyer, who can help you assess the situation and provide corresponding legal advice, including the possibility of taking legal action against the patentee.
Provide other evidence: Even if the documents provided by the patentee cannot be obtained, you can consider looking for other forms of evidence to support your rights and interests. This may include other documents, contracts, research reports, witness statements, etc. Related to patent application. These evidences may need to be verified and identified by legal procedures.