One of Sidney's most iconic roles was playing Detective Virgil Tibbs in Norman Jewison's In the Heat of the Night. In one particular scene, his character questions Eric Endicott (played by Larry Gates) — a white man — while investigating a murder, and in defencive fashion, the man slaps Tibbs for daring to interrogate him. However, instead of walking away from the slap like his character was intended to, Sidney returns the blow — something that was unheard of from a Black actor at that time.
With that scene, Sidney made history and a statement about himself as well as Black humanity. "I said to [producer Walter Mirisch], in my life, whether I'm a detective or not, and I don't care where I am, if such a thing happened to me, the likelihood is I would respond,'" he recalled in an interview. "And my response would certainly not be to absorb it."