flarepilot, I find it interesting that in the US pilots are never sued and the claim always goes against the company. The UK has a similar principle under Vicarious Liability. However, there is one important bit whereby the courts may be convinced that the employee has gone on a 'frolic' rather than a 'detour' (the actual words used) and under such circumstances the employer is not liable.
I can't speak to other countries, but in the U.S. the pilots are protected from civil litigation because they are agents acting for the principal.
The license revocation letter addressed to the NW 188 pilots who overflew MSP in 2009 asserts on the third page that the lost comm incident occured 'while you were on a frolic of your own':
http://ftpcontent.worldnow.com/kfmb/...lot_letter.pdf
Perhaps this was an attempt to deflect possible future claims of vicarious liability by the pilots themselves i.e. it was due to NW's 'faulty' R/T training, we didn't have proper classes on the DL bid system, the A320 doesn't have an ACARS chime etc. The feds' letter squarely puts the blame on the pilots since they were, it claimed, 'on a frolic'.