Legal Question in Employment Law in California

They must pay you the agreed wage for all work performed prior to notifying you of a change. They are free, however, to demote you at any time, or even reduce your pay without demoting you. Once they notify you of that change, then they only owe the new lower wage for work done after that time.

The employer is entitled to set and change hours, duties, titles, compensation, benefits, leaves, vacations, holidays, policies, rules, etc. just not retroactively. Employees have the 'right' to pay and employee benefits per the state wage and hour laws and any formal company policy that may be in place, the right to be provided a 'safe' workplace to minimize risk of injury, and sometimes are entitled by law to certain medical/pregnancy leave rights.