Software Licensing – who?s liable?

I have been a Network Administrator for a handful of companies (large and small) over the past several years, both as an employee and as a contract worker. I am concerned when I am asked by my employer to install unlicensed software.
I always warn them that we do not have licenses yet I am asked to install the software anyways. When the “S**T hits the fan” who is ultimately liable? Is their any definitive rule regarding this situation? Who will the BSA hold accountable?
How should I protect myself short of asking my employer to “sign off” on the issue(thats a joke).