What is the difference between the time bar and the last employer rule?

The purposes underlying the time-bar provisions and the last employer rule are distinct. The primary purposes of the notice and filing requirements of sections 12 and 13 are to protect employers and insurers from fraudulent claims and to facilitate prompt investigation of injurious working conditions by requiring the claimant to reveal the existence of an alleged injury or disease within a reasonable time of the claimant's awareness of its existence. Smith v. Aerojet-General Shipyards, Inc., 647 F.2d 518, 524 (5th Cir.1981). The purpose of the last employer rule is to assign liability for an occupational disease to one of several potentially liable employers or insurers and thereby avoid the administrative difficulties and delays that would accompany an apportionment of liability. Cardillo, 225 F.2d at 145.