Federal and state labor laws do not restrict an employer from requiring hourly employees to work overtime. Any prior notice given to the employees of mandatory overtime is usually at the sole discretion of the employer. Certain state and federal laws require prior notice and approval for overtime hours for certain medical professions, pilots and commercial vehicle drivers.

No Advanced Notice

No law at the federal or state level exists requiring an employer to give an hourly worker advanced notice for overtime hours. An employer can legally approach an employee seconds before her shift ends and require her to stay extra hours without regard to the employee's personal life or plans. An employer may consider overtime hours mandatory, meaning the employee has no option to refuse to work these hours unless the worker simply wishes to terminate employment and leave the job permanently.

Mandatory Overtime Restrictions

As of June 2011, 16 states across the country, including Pennsylvania, New Jersey and Texas, require prior notice and approval of overtime hours for certain health care professionals, including nurses. Under these regulations, an employer cannot force a nurse to work mandatory overtime hours and must provide reasonable notice for any needed overtime hours. These laws are in place to protect health care professionals from working long hours, which can impact the ability of nurses and other medical professionals to make smart medical decisions and may increase the risk of inadvertent patient injury.

Industries With Hour Restrictions

Certain industries, including the trucking and airline industries, have restrictions on how many continuous hours per day an employee may drive a commercial delivery vehicle or pilot an aircraft. An employer must ensure scheduling an employee extra hours does not place his total working hours for the day over the federal or state limit. Doing so is illegal and places everyone around the employee at a greater risk for injury. A company compelling an employee working in a profession with restricted operating hours to work overtime could incur both civil and criminal liability.

Collective Bargaining Agreements

Workers with union representation may negotiate for prior notice to working overtime hours with an employer during the process of creating a collective bargaining agreement. Appropriate notice under a collective bargaining agreement may vary depending on what the employees want and what the employer agrees is appropriate. A collective bargaining trumps state or federal law where no law exists to the contrary. For example, an employer cannot ask union members to accept a wage below the federally established minimum in an employment contract.