Well, I used to manage a few restaurants, and the catering industry has all sorts of laws and regulations that need to be upheld in order to retain a license to trade.
Most of the issues I'd have to contend with had to do with employee rights and health & safety issues.
Upholding relevant laws at work
I can think of two specific incidences where I've made a call to uphold "legal procedure" (I'm pretty much always fighting on the side of good in general).
The first was when I was in the kitchen going through stock. I noticed a batch of chicken (that was still sealed and refrigerated) that had passed its use by date (by one day).
The head chef, concerned with the very tight wastage budget, was adamant he was going to use the chicken. I had to convince him that there was no way we could use it. Regardless of whether it was safe to eat or not, the label clearly stated that we couldn't use it - and it would have been a serious breach of food hygiene principles to do so.
A second situation arose in a restaurant that I was working at, where I was put in charge of employee payroll.
I was instructed to enforce a "cut-off" point, where people would stop being paid in order to not "over-spend" on labour. This was regardless of whether the employees had finished working or not. They would continue working and clock out as normal, unaware that they weren't going to be paid for the last 30-60mins anyway!
Resolving ethical conflict at work
I thought that was a terrible thing to do, so I raised my concern with the GM. He was unsympathetic, saying that people would have no incentive to work quickly if they thought they'd be paid as much as they liked.
I understood that he was under pressure to meet budget - but I disagreed with this action, and felt it was my responsibility to take the issue higher. As a result, action was taken to ensure all employees were paid for the time they were on the clock.