Here is an article that may help explain this for you:
http://www.freerepublic.com/focus/f-news/2900999/posts
Here he addresses the “anti-injuction act’ you referred to:
Roberts first examines the question of whether the Anti-Injunction Act prohibits Americans from bringing suit against Obamacare at this time.
The Anti-Injunction Act provides that no suit for the purpose of restraining the assessment or collection of any tax shall be maintained in any court by any person, whether or not such person is the person against whom such tax was assessed, Roberts explains.
Amicus contends that the Internal Revenue Code treats the penalty as a tax, and that the Anti-Injunction Act therefore bars this suit, says Roberts.
The text of the pertinent statutes suggests otherwise, Roberts continues. “The Anti-Injunction Act applies to suits for the purpose of restraining the assessment or collection of any tax. Congress, however, chose to describe the [s]hared responsibility payment imposed on those who forgo health insurance not as a tax, but as a penalty. There is no immediate reason to think that a statute applying to any tax would apply to a penalty.
Congresss decision to label this exaction a penalty rather than a tax is significant because the Affordable Care Act describes many other exactions it creates as taxes, said Roberts.
Roberts thus concludes that because Congress calls the penalty for not complying with the individual mandate a penalty not a tax, the “penalty” therefore is not a “tax.”
That’s just plain whack. Looks like it will be up to us then. Time to grab a pitchfork and visit my Congressman and Senators.