My husband works as an auction manager for an auction house based in
Virginia, although the auctions are held every weekend in numerous
locations across the united states and he travels to those locations.

We are residents of and pay taxes in the state of California.

When he is waiting between auction locations (1-3 days in a week), the
company pays him a flat fee of $50 per day, even though he is
available for the entire day to troubleshoot and work.  He normally
makes $19 per hour.

Shouldn't the company be paying him $19/hr for 8 hours on those days?

The company has had many labor law infractions over the 11 years he's
worked for them, and they have been audited and fined by the IRS.

Thanks in advance for your help.  We are trying to find as much
information as we can to collect back wages as a result of this and
other infractions.

Can you please include the Labor Law statute/paragraph/section number
which supports your findings regarding this?