In 1988 the United States passed a federal labor law "Worker Adjustment and Retraining Notification Act (WARN) that requires employers with 100 or more employees to provide notification to employees 60 calendar days in advance of a mass layoff.
Federal: https://www.dol.gov/agencies/eta/layoffs/warn
California: https://edd.ca.gov/en/jobs_and_training/layoff_services_warn
Typically this takes the form of when a company does a mass layoff those affected are notified their last day of work is that day, but they are still employees (and on the payroll with full benefits) until their official termination date 60 days later.
Teradata's recent action of laying off 200+ employees on Oct 31 (Happy Halloween), did not provide them with 60 day notice, but rather 10 days, setting most of their termination dates to Nov 10.
Teradata has cleverly avoided ever issuing the required 60-day notification because the act defines a mass layoff as being between 50-499 full-time employees at a single site of employment, equaling at least 1/3rd of the workforce at that site, or 500 or more full-time employees at the site.
The act even will count the total of employees laid off at different times in the year, however Teradata's loophole is that with the majority of the workforce being virtual in the United States, there is no critical mass at a "single site of employment" which is defined in the act as follows:
Single Site of Employment
(1) A single site of employment can refer to either a single location or a group of contiguous locations. Groups of structures which form a campus or industrial park, or separate facilities across the street from one another, may be considered a single site of employment.
(2) There may be several single sites of employment within a single building, such as an office building, if separate employers conduct activities within such a building. For example, an office building housing 50 different businesses will contain 50 single sites of employment. The offices of each employer will be its single site of employment.
(3) Separate buildings or areas which are not directly connected or in immediate proximity may be considered a single site of employment if they are in reasonable geographic proximity, used for the same purpose, and share the same staff and equipment. An example is an employer who manages a number of warehouses in an area but who regularly shifts or rotates the same employees from one building to another.
(4) Non-contiguous sites in the same geographic area which do not share the same staff or operational purpose should not be considered a single site. For example, assembly plants which are located on opposite sides of a town and which are managed by a single employer are separate sites if they employ different workers.
(5) Contiguous buildings owned by the same employer which have separate management, produce different products, and have separate workforces are considered separate single sites of employment.
(6) For workers whose primary duties require travel from point to point, who are outstationed, or whose primary duties involve work outside any of the employer's regular employment sites (e.g., railroad workers, bus drivers, salespersons), the single site of employment to which they are assigned as their home base, from which their work is assigned, or to which they report will be the single site in which they are covered for WARN purposes.
(7) Foreign sites of employment are not covered under WARN. U.S. workers at such sites are counted to determine whether an employer is covered as an employer under § 639.3(a).
(8) The term “single site of employment” may also apply to truly unusual organizational situations where the above criteria do not reasonably apply. The application of this definition with the intent to evade the purpose of the Act to provide notice is not acceptable.