A person could have legal claims against a third party. However, the person looses his remedy to enforce such claims either due to statute of limitation, case-law or otherwise. When the remedy is lost, the claim is barred.
Example a State Statute (Michigan) mentioning Barred Claim
MCLS § 600.5866 Revival of barred claim; written acknowledgment of obligor.
Express or implied contracts which have been barred by the running of the period of limitation shall be revived by the acknowledgment or promise of the party to be charged. But no acknowledgment or promise shall be recognized as effective to bar the running of the period of limitations or revive the claim unless the acknowledgment is made by or the promise is contained in some writing signed by the party to be charged by the action.