Not officially, yet. Although the Department of Labor (DOL) has issued no rules as of summer 2011, a request for information (RFI) issued in December 2010 does provide some guidance on an employer's notice requirements, as follows:
“In order to facilitate an employer's ability to provide appropriate space for expressing milk, the DOL encourages nursing employees to give employers advance notice of their intent to take breaks at work to express milk. The DOL believes that a simple conversation between an employee and a supervisor, manager, or human resources representative about the employee's intent to take breaks for the purpose of expressing breast milk would facilitate an employer's ability to make arrangements to comply with the law before the nursing mother returns to work.
"The Department notes that an employer may ask an expectant mother if she intends to take breaks to express milk while at work. Doing so informs employees of their rights under the law and allows the employer the opportunity to make any necessary adjustments to comply with the law."
The DOL noted that until any further guidance is issued, the RFI provides useful information for employers to consider in establishing policies for nursing employees because it contains the DOL's preliminary interpretations of the law's requirements.
Source: Break Time for Nursing Mothers, http://www.dol.gov/whd/nursingmothers/.