Both federal labor laws require an employer to file a publicly available advance notice if they are anticipating mass (50 or above) mass layoffs. And, many states have incorporated these rules and regulations into state labor laws.
"The Worker Adjustment and Retraining Notification Act (WARN) protects workers, their families, and communities by requiring employers with 100 or more employees (generally not counting those who have worked less than six months in the last 12 months and those who work an average of less than 20 hours a week) to provide at least 60 calendar days advance written notice of a plant closing and mass layoff affecting 50 or more employees at a single site of employment."
"Advance notice gives workers and their families some transition time to adjust to the prospective loss of employment, to seek and obtain other jobs, and if necessary, to enter skill training or retraining that will allow these workers to compete successfully in the job market. Regular federal, state, local, and federally-recognized Indian Tribal government entities that provide public services are not covered."
"Employees entitled to notice under WARN include managers and supervisors, as well as hourly and salaried workers. WARN requires that notice also be given to employees' representatives, the local chief elected official, and the state dislocated worker unit."
"DOL's Employment and Training Administration (ETA) administers WARN but has no enforcement role in seeking damages for workers who did not receive adequate notice of a layoff or received no notice at all. Some states have plant closure laws of their own. Employers considering a layoff can contact the State Dislocated Worker Unit to find out more information on notice requirements in their state."
Of course, there are exceptions:
"There are three exceptions to the full 60-day notice requirement. However, in all cases, notice must be provided as soon as it is practicable. When notice is given in less than the 60-day timeframe, the employer must include a statement of the reason for providing less than 60 days’ notice in addition to fulfilling the other information notice requirements. The exceptions to providing the full 60-day notice are as follows:
• A "faltering company" is not required to give notice of a layoff or plant closing when, before the plant closing, it is actively seeking capital or business, which if obtained would avoid or postpone the layoff or closure, and if it reasonably believes that advance notice would hurt its ability to find the capital or business it needs to continue operating;
• A business is not required to give a full 60-day’s notice if it could not reasonably foresee business circumstances that led to a layoff or closing at the time that the 60-day notice would have been required, (e.g., a business circumstance that is caused by some sudden, dramatic, and unexpected action or conditions outside the employer’s control like the unexpected cancellation of a major order); or
• A business is not required to give notice if a layoff or plant closing is the direct result of a natural disaster (i.e., hurricane, flood, earthquake, tornado, storm, drought, or similar effect of nature)."
Some useful references:
As with all things, forewarned is forearmed.