The Human Rights Campaign -- the lesbian, gay, bisexual and transgender civil rights organization -- did not find find a David Letterman joke last night about the appointment of transgender Amanda Simpson to a senior position at the U.S. Department of Commerce funny.

The group sent a letter today to Letterman and CBS Corp. expressing disappointment and asking for a public apology.

In a skit during Letterman's opening monologue, the Late Show host announced Simpson's historic appointment and revealed that she is transgender, displaying a photograph of her. The show's announcer, Alan Kalter, then feigned "trans panic," implying he had some prior relationship with Simpson but was not aware of her gender history, and ran yelling from the stage.

In the letter, the Human Rights group writes: "You may not be aware that the punch line in your skit has been used as a defense in nearly every hate crime perpetrated against transgender people that has come to trial. For example, the 'trans panic'defense was infamously used by Allen Ray Andrade, who was convicted in 2009 of beating 19-year-old Angie Zapata to death with a fire extinguisher after learning of her gender history."

Simpson, 48, who started her job yesterday as senior technical advisor to the Department of Commerce, has said the fact she was "Mitch" before becoming Amanda is relevant if only to illustrate the need for greater equality.