Before laying off 100 or more, consider whether WARN Act notification is required.

The federal Worker Adjustment and Retraining Notification Act requires employers with 100 or more full-time employees to provide written notice of impending plant closings and mass layoffs at least 60 calendar days in advance. The WARN Act defines a plant closing as the "permanent or temporary shutdown of a single site of employment, or one or more facilities or operating units within a single site of employment."

Recent case: Resorts World Casino in Queens, N.Y., is a sprawling facility. At the time the casino implemented a mass layoff in 2014, it had more than 30 distinct food and beverage operations. An all-you-can-eat restaurant was losing money, so the casino closed it, costing 177 employees their jobs. The casino did not provide a WARN notice and some employees sued.

A trial court initially dismissed the case, ruling that the restaurant was not an operating unit; therefore, no WARN...