Cashier's checks are insured against insolvency of the issuing bank by the FDIC, so they are backed by the US Government. However, that scenario would be fairly

Cashier's checks are insured against insolvency of the issuing bank by the FDIC, so they are backed by the US Government. However, that scenario would be fairly rare (even in the scope of bank insolvency), as the FDIC's requirements to issue cashier's checks are fairly strict - enough so that it's common for smaller banks and credit unions to actually pay a different bank to issue their cashier's checks. Take a close look at a cashier's check issued by a credit union, for example, and you will typically see that it is actually drawable against a commercial bank somewhere else that the CU contracts for this purpose. Western Union used to have a business unit that coordinated these arrangements and handled the technical side (verification service etc), but I think they spun it off to a different payments company.