Why Sue? Why wouldn't you Impeach?

Why would a group of law makers sue President Obama over the legality of the war in Libya?

As was reported in Politico:

"A bipartisan group of House members announced on Wednesday that it is filing a lawsuit charging that President Obama made an illegal end-run around Congress when he approved U.S military action against Libya.
“With regard to the war in Libya, we believe that the law was violated. We have asked the courts to move to protect the American people from the results of these illegal policies,” said Rep. Dennis Kucinich (D-Ohio), who led the 10-member anti-war coalition with Rep. Walter Jones (R-N.C.)The White House is expected on Wednesday to deliver to Congress a much-anticipated report detailing military activity in Libya.
According to Kucinich, the suit will challenge the Obama administration’s “circumvention of Congress and its use of international organizations such as the United Nations and the North Atlantic Treaty Organization to authorize the use of military force abroad.”"

Honestly, there is already a legal mechanism in place to deal with this sort of thing. Since President Obama is clearly in violation of not only Article 1, Section 8 of the Constitution of These United States of America, and the War Powers Resolution of 1972, all that needs to be done is file Articles of Impeachment for High Crimes and Misdemeanors.

I asked my representative, Congressman Paul Broun, MD (R-GA), well actually I demanded of him both via e-mail and in person, that he take the lead in impeachment of the president. Dr. Broun, of course, has a bit of a stake in the government continuing it's "business as usual" and has no interest in actually defending the Constitution. When I spoke with him last month at a "town hall" style forum at the Veterans of Foreign Wars Post 2872, Dr. Broun's best excuse for doing nothing was to say that he is "only one voice" in Congress. I reminded him that he was "My" voice in Congress and that as a citizen of the State of Georgia and his constituent, he actually works for me, as does the president, and would be held accountable for his inaction.

We should all stand up and ask "Why a law suit? Why not impeachment"?