Think about why you are firing the employee. Why? Think about the following from the workforce.com's ADA 'Association' Claim:
Terminating an employee in a fit of pique or bad temper is never a good idea. This may be evidence of a discriminatory intent at worst and grounds for filing an employment lawsuit at best."The U.S. Court of Appeals for the 10th Circuit in Denver reversed, holding that the Trujillos raised a reasonable inference of PacifiCorp’s discriminatory motive to establish a prima facie case of association discrimination. The time proximity between Charlie’s expensive treatment and PacifiCorp’s investigation and termination of the Trujillos supported an inference of discrimination. The Trujillos also presented evidence that other employees accused of similar workplace misconduct were not fired. Trujillo v. PacifiCorp., 10th Cir., No. 06-8074 (5/7/08).
Impact: Even if there is a legitimate business reason for terminating an employee, disparate treatment of similarly situated employees by a company suggests a reasonable inference of pretext. Employers are advised that when considering taking action against workplace misconduct, they should take action that is consistent and is in line with company policy."
Along with the advice above, I would add two things: 1) think about twice about why you are terminating the employee and 2) document everything.