I've been saying for years, leftists generally hate the rule of law. They just do. The rule of law means they are restrained from doing what they think is best. Therefore, they hate it. There is infinite evidence of this. They openly question whether we should follow the law at every turn, from the top (Justice Breyer and President Obama) to the bottom (pretty much every "occupy" protestor).
We actually had a majority of the federal legislature decry a Supreme Court decision that merely said -- in reference to Lily Ledbetter -- that you cannot punish a company under the law, unless it actually breaks the law. Not to mention the case that said the federal legislature cannot restrict political speech by a person or group of persons, just because they are organized a certain way under the law, that also got massive opposition from liberals.
Time and again, the left just demonstrates a very clear and palpable hatred for the rule of law. They would have us ruled by enlightened people who would be free to make up rules as they went along.
Impeachment is a stupid idea. It will likely give the country little benefit to shave a mere year or so off his presidency, and generate massive animosity that will increase the liklihood of another law-hater being elected.