To my knowledge there is no such law. However, there are two things that do figue into this problem. The first is that if the employer had promised your husband, at or before he was hired, that the hours were to be Sunday through Thursday, with Friday and Saturday off, then that can be considered a term of employment. There is a law that prevents an employer from lying or otherwise deceiving employees or potential employees about a term or condition of their employment.
If you could show that the previously mentioned work shedule was a promise made by the employer in writing or verbally, then you might claim that the employer has broken that promise with their current work schedule. However, valid defense to such a claim of a breach of contract is that the employer had to make reasonable business changes to the work schedule in order to fulfill their business goals.
I would not advise your husband to make such a claim to the employer as he is likely to be terminated. California is an at-will employment state. That law really means that the employer can terminate an employee at any time, with or without a reason. The exceptions are for terminations on the basis of a protected category such as race, religion, age, etc.
The other issue is that the employer has to be paying overtime to your husband and the others for all of this time worked. If they are not, then that is a violation of the federal Fair Labor Standards Act. More information on that act can be found at
freeadvice.com/gov_material/dol-reference-guide-to-fair-labor-standards-act.htm.
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Mark B. Replogle