I have no experience in world building or legal stuff, but I would imagine proof might be part of the actions leading up to said event, such as planning and preparing to execute said plan.
Then, disproving might be showing a chain of events that might lead to an accidental predation.
Bad TL;DR:
Employers rarely get penalized for wage theft, because they settle often, especially because employees are encouraged to settle because 1) they get their money faster and 2) because the odds of the company paying go down if they don’t settle.
Oregon wants to discourage companies from their current bad behavior because at the moment there’s very little to dissuade a company from not paying and then settling, especially because they avoid any repercussions.