Since Canada and the USA are governed by their own laws, if someone if Canada is performing a service which must comply with US laws and they don't comply, how would that person be charged or prosecuted?

What law(s) are they breaking?

Hello t:

Countries enforce their own laws. Therefore, there isn't any US law that needs to be obeyed in Canada. In fact, if you violate a law while in Canada, it's going to be Canada that prosecutes - not the US.

excon

If the work is being done in Canada there is no enforcement of criminal laws.

But this appears to be a civil issue, if the contract states they have to follow US laws ( employment, safety and so forth) if they don't then they are in default of the contract and the other party can sue in civil courts for any remedy listed in the contract.

Since the parties signed to follow specific rules not doing so allows the other party to sue for damages