Unless it's a contracting or union position, what you get is something resembling a contract, but your agreement to it comes with the mutual understanding between you and your employer that no effective enforcement body exists to uphold your interests.

If it says "you work 40 hours per week and have 4 weeks of paid vacation" and your employer, EVEN IN WRITING, compels you to work 60 hour weeks and not take any vacation at a later date, then your only real option is to find work elsewhere. The Department of Labor won't have your back and you likely won't have enough money to afford a lawyer to fight on your behalf longer than the corporate lawyers your company has on staff.

Many programmers don't get treated this way because of the market, but abusive treatment of employees runs rampant in blue collar professions.

Need proof? Look at how few UNPAID weeks of maternity leave new mothers are entitled to under the law. This should tell you everything you need to know.

I have personally seen women return to work LESS THAN A WEEK after delivering a baby because they couldn't afford to not do so.