If you have kept up with the news, you know that Obama has been signing bills and supporting them frequently. Some of those bills are deemed unconstitutional. However, those bills aside, he actually has already done many things that can be considered unconstitutional.
However, there is one action that is proven to be without a doubt unconstitutional. Resident (spelling is intentional) Obama declared war without prior approval from Congress and that is unconstitutional. In fact it justifies an impeachable high crime and misdemeanor.
This is all under article II, section 4 of the Constitution.
That is all we have for now, but if you’re interested in the specific bill you can view it here: