Legality issue related to cats/fleas, anyone know about "tenant rights"???

Its going to end up being your issue no matter how you slice it. I know it doesn't seem fair but they're your cats and whether they attracted the fleas or had them all along, its going to be your responsibility. The only way you'd have a claim is if you didn't have fur bearing pets and all of a sudden you got infested. Sorry but its probably covered in your agreement and/or in the PA tenant/landlord legislation. You could consult an attorney but that would be more money out of your pocket. Treat the premises and then treat your cats too. Talk to your vet. There are some really effective treatments out there.