No there isn't. The entire burden is on the prosecution.
The minute George attempts to make the legal claim of "self defense" he will have to offer his version of the story. That version is going to have to stand up to heavy scrutiny, and if he gets on the stand to a vigorous cross examination as well.
The state can lead off by presenting a very limited version of events which will force George to respond:
* George saw Trayvon walking alone
* George followed him in his car
* George exited that car and continued following Trayvon
* George and Trayvon scuffled
* George shot Trayvon
None of these facts are in dispute. As such, George is going to have to present a version of events that allows him to invoke self-defense -- and once he starts doing that, now he has to make it believable to six people in a jury box, none of whom were bright enough to get out of jury duty*.
See, here's the thing, George is in a bad situation to start from, not a neutral situation. The completely-bare facts are that _
George shot Trayvon_. Absent any further testimony, George goes to jail for Murder Two. As mentioned before, those of you who are under the impression that this is an open and shut case for the defense right now are in for some serious potential heartbreak. I haven't yet come to anything I'd describe as a concrete conclusion WRT this case, but I can say that by default I lean towards convicting George because he took several actions that escalated the situation, rather than defused it:
* Followed Trayvon in his car
* Exited the car to continue following
* Confronted Trayvon
These taken together are enough for me to decide that George is clearly at fault for this death. Whether I would convict him of Murder Two is up in the air as I only have so much time and haven't gone through all the evidence and built a timeline yet, but I can guarantee this is the angle the prosecution will take to destroy George's (expected) self-defense claims; that George re-established contact with Trayvon several times, had the opportunity to break away and let law enforcement handle it, and did not do so. And it has a reasonably good chance of success, because Joe Ordinary is not going to have much sympathy for wannabe heroes like George.
(We haven't even got into
voir dire yet and its possible effects; good luck getting any gun owners on that jury, for example, as I'd expect the prosecution to move to strike them all on "predisposed towards guns being for self-defense" -- and if a judge grants that every time, George goes to jail. Not as easy to do that for any black jurors, though you can bet the defense is going to want to do so.)
* I wish I was joking.