It is normal, after a tragedy or monstrous attack, to ask if it could have been prevented. Invariably the answer is a qualified "yes." Things could always have gone differently. Tim McVeigh could have been in a horrible traffic accident while buying the supplies to make his bomb- thus preventing him from blowing up a Federal Building in Oklahoma. One of the 9-11 attackers could have tripped and fallen on the way to the cockpit, giving the flight crews time to secure the door- preventing at least part of that monstrous attack.
In some cases, the answer is a much less qualified, and more specific "yes." The parents of the kids who committed the Columbine massacre could have payed attention to what their kids were doing, for instance. Back to 9-11, we could have had a robust and efficient illegal immigration policy which would have deported most or all of the attackers when their Visas expired.
In the case of the Aurora, Colorado attack, that question is being asked. Unfortunately, a lot of hand-wringing is occurring, even though the answer seems to be that more general, "well things could always have gone differently." Specifically, much hay is being made of the fact that Mr. Holmes's psychiatrist referred him to the college's "Behavioral Evaluation and Threat Assessment team," as a potential threat.
The reporting seems to suggest that team somehow let the ball drop. It is never explicitly stated, but the argument that they "should have done more" is either "just asked" in the headline, or insinuated through the reporting. However, I'm a firm believer in the facts, and the facts don't bear that out at all. Not the facts we currently have, at any rate.
Yes, his psychiatrist did, indeed, refer him to the BETA team. Yes, she considered him a threat. However, she had no specific information about any specific threat (or she should have called the police). After she referred him to the BETA team, whose specific powers are unclear from current reporting, he dropped out of school. At that point, with the possible exception of barring him from campus, the University of Colorado had no interest in Mr. Holmes, nor any authority to do anything to prevent any actions on his part.
This hand-wringing is stupid. Worse, it is actually counter-productive. You see, if there was some way to prevent this, then we have someone (other than the shooter) to blame. If we have someone other than the shooter to blame, then all those people saying, "Hey, if someone had been allowed to carry a concealed handgun, things might have gone differently" can be safely ignored, because "the system broke." Also, if someone is to blame (other than the shooter), we can safely ignore the question of Evil.
James Holmes is Evil. He was a Ph.D. candidate, showing that he at least had the basic skills and judgment to succeed at life, generally. He may also have had some psychological issues, but we're not talking someone in complete disconnect from reality, here. James Holmes planned this attack very carefully. He even, according to reports, set up a trap for the police to give him more time to kill innocent people. James Holmes is Evil.
Nothing was going to stop him from attempting this act. No one had any authority to prevent any of the things he did- up until he started shooting at people- nor should they. This question of if more could or should have been done is useless at best, and harmful at worst.