The Fair Labor Standards Act is the only thing I can think of that applies to all employers (....but there's lots I do not know). I am not aware of anything that prevents a company from doing what it wants.
However, when trouble arises and an employee wants to fight an employer in court, the employer is expected to follow their own written policies, labor contracts, etc. Do they have any policy dictating notices of change? How has it been enforced / put into practice.
Just because an employer thinks or you think this might disqualify you from unemployment does not mean it will. If the change and it's implementation is deemed unreasonable by unemployment - you will qualify (provided you meet other eligibility requirements.)
Have you tried talking to them? Is it just the new demand that bothers you? Lots of people do not like change immediately. Perhaps if you give it some time, you will find the time is sufficient. I would consider letting them know when, how and why it isn't whenever it isn't. Be aware - silently giving it too much time could be taken as acceptance.