The US Constitution makes a clear distinction between holding ideas, and engaging in criminal acts as a result of those ideas. You are allowed to promote any idea, no matter how reprehensible, but not to break the law as a result of holding that belief. 

Other countries have a vaguer idea of the relationship between ideas and acts. Anti-fascists in the USA write as if they want the USA to abandon the First Amendment, though rarely do they put it as clearly as that. Not only that, but they are inconsistent in their application of their own rule. Some of them openly advocate violence against people who hold far-right ideas which may lead to violence against innocent people. A dramatic recent example was the murder of six Sikhs in Milwaukee on August 5 by a member of 'Hammerskin Nation'. Anti-fascists use this massacre as a vindication of their attempts to 'shut down' that white extremist organization. 

But when a gay activist shot a guard at the conservative Family Research Council, anti-fascists didn't see this as a reason to 'shut down' LGBT extremist groups. Most of the mainstream media played down the motive for the shooting, the opposite of the behavior in cases of far-right political violence, and the opposite of what the anti-fascist analysis of this society would predict:

http://video.foxnews.com/v/1794444048001/liberal-media-downplays-motive-of-frc-shooter/

But conservative channel Fox News asked if 'reckless' left-wing propaganda might have spurred the attack:

http://video.foxnews.com/v/1809171658001/watchdog-groups-reckless-criticism-led-to-frc-shooting/?playlist_id=86856

Anti-fascists are quick off the mark to allege that conservatives are responsible for stirring up violence. A bit too quick, in some cases. When a nut murdered some innocent people and injured a politician in Tucson last year, professional anti-fascist Chip Berlet had no doubt about his motives:

"From a moral viewpoint Rep. Gabrielle Giffords is the victim of demagogues such as Glenn Beck and his allies at Fox News and in the Tea Party Movement." http://pacificaforum.org/anti-fascists-circle-over-arizona 

As targets of this attempt to selectively circumvent the First Amendment, one can understand the Fox journalists' treatment of the gay maniac vs. the Family Research Council case.

The American Family Association correctly points out that, according to its own standards, the anti-fascist Southern Poverty Law Center is responsible for the shooting - it blames ideas for criminal violence.

Though I argue that anti-fascism today is mostly an ally of Zionism, there are exceptions. Anti-Racist Action's website contains a link to a story about a pro-Israel ad on San Francisco buses, criticizing it as a 'sick Zionist advertisement':

http://abclocal.go.com/kgo/story?section=news%2Flocal%2Fsan_francisco&id=8769862

So... of those ideas which logically lead to violence against innocent civilians, which of them would one be justified in attempting to suppress? The answer has to be either

• none of them, or
• all of them.

The anti-fascist answer is 'those ideas which lead to violence which we feel particularly offended by'. The US Supreme Court is unlikely to endorse this rather arbitrary interpretation of the law, so anti-fascists will probably continue to be more of a nuisance than a danger. Their main role will continue to be to hype up white racism, and downplay Jewish supremacy, in this society.

I suppose I have to add that I have zero sympathy for the ideas of the Family Research Council and even less for Hammerskin Nation. Just in case anyone is too dumb, or dishonest, to see that nothing in the above implies that I do.