They are bringing suit under the California WARN statues which really doesn't address the root of the issue: Employment at will. The US is the ONLY developed country which makes Employment at will public policy for non-union employees. All states in the US make at-will policy except Montana.

A much better system would be "Just Cause". Where causes for termination have to be defined, and can't be nebulous. The rest of the developed world implements this as public policy.