If you think about that, it makes sense. How else could we, the FAA, know what we are looking at. An applicant for a U.S. certificate based on a foreign pilot certificate must hold a valid U.S. medical certificate or a valid foreign medical certificate. If a foreign medical certificate is used it must also include an English translation or be accompanied by an English translation signed by an official of the foreign aviation authority that issued it. The medical qualifications for the issuance of a certificate under FAR 61.75 often causes confusion.
Some foreign countries stamp their pilot certificates to show continued medical qualifications.
Without a current medical qualification stamp the foreign pilot certificate is invalid and could not be used to obtain a U.S. pilot certificate under 61.75, even if accompanied by a valid U.S. medical certificate. Some foreign aviation authorities renew their pilot certificates by reissuing the pilot certificate after the pilot proves medical qualification. No proof of such qualification is evident to an FAA inspector by looking at the foreign pilot certificate. We would not know whether it is a valid certificate needing a valid medical certificate or whether that particular aviation authority just reissued the certificate after the applicant showed proof of medical qualification. Therefore, in this situation, a foreign pilot needs to be prepared to prove his foreign medical qualification or, simply, obtain a U.S. medical certificate.