Speaking on the Senate floor Tuesday, U.S. Sen. Rand Paul, R-Ky., announced he is filed a brief to join a lawsuit challenging President Obama's recess appointments.In December, the president sidestepped the Senate by naming three new members to the National Labor Relations Board and installing former Ohio Attorney General Richard Cordray to lead the Consumer Financial Protection Bureau. The Constitution allows the president to "fill up all vacancies that may happen during the recess of the Senate" which most scholars believe helps the continuity of the federal government by temporarily filling positions. But the National Right to Work Foundation, the National Federation of Independent Business and other business groups have filed suit, claiming Mr. Obama violated the law.Paul says the president has disregarded the separation of powers and condemned what he called Mr.Obama's "unconstitutional usurpation of power."Check it out:Earlier this month, U.S. Rep. Brett Guthrie, R-Ky., also blasted the president for bypassing Congress and invoking recess appointments.