Verify a US trademark by USPTO serial number (8 digits) or registration number. Returns the word mark, LIVE/DEAD status with the detailed status description and date, filing and registration dates, current owner (name, entity type, citizenship), mark type (trademark / service mark / certification mark), standard-character flag, abandonment date when applicable, and the international classes covered with their descriptions. Authoritative real-time USPTO data — confirm a mark exists and is active before relying on it for clearance, licensing, or due-diligence work. Lookup is by number only (no text search); siblings: /api/patents/search, /api/law/case-verify.