George Zimmerman to be charged in Trayvon Martin shooting, law enforcement official says

[The Velveteen Ocelot]

42. Premeditated murder = first degree murder.

One of the required elements of the offense of first degree murder is premeditation.

I think it's pretty doubtful - or at least, not easily provable - that Zimmerman originally set out to shoot Martin. It's more likely that he decided he was going be the Big Shot Neighborhood Watch Cop Wannabe and follow, then harass and intimidate him into leaving the area. Then something happened - we don't know exactly what - that made him decide to use his gun. Technically, premeditation can occur in a very short period of time, but proving it under these circumstances will be difficult. The prosecutor has a much better chance of getting a conviction by charging Z with the lesser offenses of 2nd degree murder (intent to kill but without premeditation) and/or manslaughter (intentionally acting in a way that could cause death but without specific intent to kill).