Under Chapter 21, an Employer Does Not Have to State All the Reasons for an Employee's Termination in the Termination Letter
Generally, an employer does not have to—and likely will not—tell an employee all the reasons they fired him.
Under the ADA, Full-Time Teleworking Is Rarely a Reasonable Accommodation
Telework and the ADA.
Retaliation under Chapter 21 of the Texas Labor Code
Opposition to a discriminatory practice is a protected activity irrespective of the merits of the underlying discrimination claim.

