On January 4, 2012, President Obama made three so-called recess appointments to the National Labor Relations Board (NLRB) while the Senate was not in recess. These appointments were unprecedented—no other president has made recess appointments while the Senate was in session.

A year later, the U.S. Court of Appeals for the District of Columbia unanimously held that the president's appointments violated the Constitution.

The Senate decides when it is in session – not the president.

Were it otherwise, there would be no point to the Senate's constitutional "advice and consent" power at all, and the Senate could return from lunch one day to find there's a new Supreme Court justice.

The White House claims these appointments were within the president's power, but the record shows Democrats have opposed such tactics. In 2007, Senate Majority Leader Harry Reid stated that over the Thanksgiving holiday, he would be "keeping the Senate in pro forma [session] to prevent recess appointments" that could have been made by President Bush – who, by the way, respected Reid's move and didn't make appointments.

By making unconstitutional appointments to the NLRB, President Obama has invited legal challenges to each of the invalid board's decisions.

The NLRB has just one Senate-confirmed, constitutional member, so it has no quorum. However, the invalid appointees have participated more than 950 decisions, including nearly 300 since the federal court found them unconstitutional. They have ignored the federal court's ruling. These legally invalid decisions and regulations only threaten the rights of American workers – the very people the board is intended to protect.

The NLRB is tasked with creating stability for workers, employers, and unions — this allows America's businesses to focus on succeeding and growing. The board conducts union elections and works to prevent (or remedy) unlawful practices on the part of employers or unions. We must protect workers and employers alike. Continued board activity without valid confirmed members does the exact opposite.

We have introduced legislation to address these appointments in both the House and Senate. The Preventing Greater Uncertainty in Labor-Management Relations Actwould prohibit the NLRB from taking any action that requires a quorum until board members constituting a quorum have been confirmed by the Senate, the Supreme Court issues a decision on the constitutionality of the so-called recess appointments, or the first session of the 113th Congress is adjourned. The House of Representatives passed this legislation in April, and we're hopeful the Senate will take it up soon to bring certainty to the NLRB.

President Obama earlier this year submitted to the Senate a full slate of five nominees for the NLRB. Unfortunately, two of these nominees are the very individuals who accepted unconstitutional recess appointments last year and continue to participate in decisions since the court ruled that they are invalid. Their actions show a troubling disrespect for the Constitution and the principle of separation of powers. They are also adding to the deep uncertainty U.S. workplaces now face with labor law.

The president should withdraw these two nominations and submit new names for the Senate to consider. Until then, our legislation should be passed into law to provide certainty to the businesses and workers who rely on a functioning NLRB and to protect against the unrestrained tyranny of the executive branch of government.

Sen. Lamar Alexander (R-Tenn.) of Tennessee is the senior Republican on the Senate Committee on Health, Education, Labor and Pensions. Rep. Phil Roe (R.-Tenn.) is chairman of the House subcommittee on Health, Education, Labor and Pensions.