1) For Illegally Changing Obamacare: It doesn't matter if the Affordable Care Act is called "Obamacare;" Barack Obama doesn't have the authority to unilaterally change the law. Changes to the law have to be made by Congress and then signed into law by the President. Barack Obama has broken the law repeatedly by making at least 23 unilateral changes to the law. Saying, "The Republicans won't work with us," or more disturbingly, "It's politically convenient," is not an excuse for overriding the Constitution of the United States.
2) Engaging In An Illegal War In Libya: While the President is the Commander-in-Chief, the Constitution gives Congress the ability to declare war. In the modern era, that has just meant an authorization of force from Congress, which Obama did not pursue. Additionally, we've tended to give Presidents the benefit of the doubt when American lives are at stake. However, in Libya, Obama didn't seek the permission of Congress and we had no national security interest in Libya. In other words, Obama's real justification for bombing that country and overthrowing its government was that HE FELT LIKE IT. Using the exact same precedent, the next President could bomb Mexico or Cuba without Congressional authorization. Incidentally, bombing either of those nations would probably make more sense than bombing Libya, although that's not saying much since our intervention there has been a complete disaster.
3) Lying To Sell Obamacare To The American People: When Barack Obama told the public if they liked their plan, they could keep their plan, he was lying. When he told Americans if they liked their doctor, they could keep their doctor, he knew it wasn't so. When he told Americans Obamacare would cut costs by $2,500 for the average family, he was deliberately misleading the public. For a President of the United States to PERSONALLY spend months telling deliberate falsehoods to the American people in order to convince them to support something as massive as a government takeover of the health care system is beyond the pale. If the willful lies Barack Obama told to sell Obamacare don't merit impeachment, then there are no lies that a President could tell to the American people big enough to merit impeachment.
4) Violating Immigration Law And Illegally Implementing The DREAM ACT: Simply put, Barack Obama has ceased to enforce most immigration law. As Senator Jeff Sessions has noted, “at least 99.92% of illegal immigrants and visa overstays without known crimes on their records did not face removal.” In other words, we've already stopped deporting anyone other than SOME hardcore criminals and gang members. Additionally, when the DREAM ACT didn't make it through Congress, Obama simply implemented it ANYWAY. Not only is he explicitly telling illegal aliens they can stay in the United States, he's illegally giving them work permits that he has zero right to offer. Even if Congress is too split on the issue to unify and put a stop to what Obama's doing, that doesn't change the fact that it’s flatly illegal. If this is allowed to stand, tell me ANY LAW on the books that the President is obligated to enforce?
5) Releasing 5 Taliban Terrorists In Exchange For Deserter Bowe Bergdahl: Barack Obama was legally required to alert Congress 30 days before he released terrorists from Gitmo. Not only did he fail to do so, but more seriously he released five high level terrorists who he knew were likely to help kill Americans in the future. One of the terrorists has ALREADY SAID he intends to go back to Afghanistan to fight America. Barack Obama spent a lot of time bragging about getting Bin Laden, but he just released five Bin Ladens back into the world and a lot of Americans who didn't desert their country are likely to die because of it.