In 2012, conservatives thought for sure that the Individual Mandate in ObamaCare would be struck down because -- for the first time ever in this country -- it would levy a penalty on Americans for not buying something. Thus, if the individual mandate was found unconstitutional, the whole law would be nullified because it did not include a single severability clause. However the conservative Supreme Court, led by Chief Justice Roberts, upheld ObamaCare because, in their opinion, the mandate for not buying health insurance was a tax and the government has a legitimate and constitutional power to levy taxes.
Many on the right were fuming that a conservative court would do such a thing. But, it just might be that The Supreme court had actually sealed the coffin on ObamaCare by calling the mandate a tax. By doing so, either knowingly or unknowingly, it established that it may be unconstitutional because the law originated in the Senate instead of the House of Representatives. This, then, was a violation under something called the Origination Clause. A clause that clearly says that any law involving an increase in revenues (taxes) must originate in the House of Representatives.
Seizing on that very nuance of constitutional law, the Pacific Legal Foundation -- on behalf of a gentleman by the name of Sissel -- has filed suit in federal courts to invalidate the Individual Mandate. Sissel, himself, has standing in the courts because he does not have health insurance; does not want health insurance; and, is being forced to buy insurance because of the tax (the Individual Mandate).
Currently, the suit is on temporary hold in U.S. District Court in the District of Columbia; pending the outcomes of other lawsuits involving ObamaCare. However, if it is litigated successfully in that court, the next stop would be the Supreme Court. This time, in both a twist of irony and fate, Roberts' court may find ObamaCare unconstitutional on the very basis that it had found it to be constitutional in 2012.
Supreme Court upholds individual mandate, ObamaCare survives: http://www.foxnews.com/politics/2012/06/28/supreme-court-upholds-individual-mandate-obamacare-survives/
Tax-raising Affordable Care Act started in wrong house of Congress: Sissel v. United States Department of Health & Human Services: http://www.pacificlegal.org/cases/Sissel-3-1374
Origination Clause: http://en.wikipedia.org/wiki/Origination_Clause