This article came across my feed, and I must say I am pleased. The AQHA has (finally!) made lip chains illegal in halter classes, to go into effect January 1st, 2016. There is already a petition to reverse the decision (I'd post the link, but I really don't want to boost that signal).
I wish any of the arguments went more into the quote from the AHQA president that "the use of lip chains in halter classes is not the intended use for lip chains," with which I heartily concur. Lip chains are, to over simplify, a form of physical sedative. They can be very useful for veterinary procedures where chemical sedation isn't needed, is contra-indicated, or isn't enough. Even in those cases, the risk of damage to the horse's mouth is huge, and I prefer to wrap the chain (2-3 layers of vetwrap is my preference, but disinfected electrical tape will work in a pinch). The risk for injury is exponentially increased if the horse is moved while wearing a lip chain- say, to walk & jog in a show class.