Artful Dodger: Um... it appears they are.

"The reason most law enforcement agencies either issue or permit their officers to carry hollow-point ammunition is that when deadly force is authorized—when the immediate threat of serious physical injury or death to the officer, their partner, or someone else is present—hollow-point rounds have a better chance of stopping that threat without the risk of over penetration. In other words, the possibility of a through-and-through shot hitting someone it was not intended to hit is lessened. The goal is to step the threat without injuring or killing someone else in the process, and hollow-point ammunition helps do that."

http://www.lawofficer.com/article/tactics-and-weapons/short-history-hollow-points