U.S. vessel can get a Statement of Voluntary Compliance-Maritime Labour Convention (SOVC-MLC).
I sail world-wide and I’ve never had an issue with PSC using the SOVC-MLC that was issued to my ship.
In any case the union contract requirements are in general higher then the MLC requirements.
NAVIGATION AND VESSEL INSPECTION CIRCULAR (NVIC) NO. 02-13
Statements of Voluntary Compliance (SOVC)
Q. Will foreign port state control officers in MLC ratifying nations accept a SOVC as
evidence the vessel is in compliance with the MLC?A. Foreign port state control authorities are under no obligation to accept a SOVC as
evidence of MLC compliance. However, the Coast Guard has sent letters to each of the Port State Control MOU authorities detailing our voluntary MLC inspection program and the issuance of SOVCs for those vessels found to be in compliance.