Was the Senate in session or not? Who decides?

Understand that the three 'recess' appointments to the NLRB are in total disregard for Constitutional imperatives that defeat Obama's claim of having the right to declare "pro forma sessions" to be without authority.  

Article I, Section 5, of the Constitution states that neither house of Congress may adjourn for more than three days without the consent of the other house. The House of Representatives did not consent to a Senate recess of more than three days at the end of last year, and so the Senate, consistent with the requirements of the Constitution, must have some sort of session every few days.

The president and anyone else may object that the Senate is conducting “pro forma” sessions, but that does not render them constitutionally meaningless, as some have argued. In fact, the Senate did pass a bill during a supposedly “pro forma” session on Dec. 23 [the two month payroll tax ‘holiday’] , a matter the White House took notice of since the president signed the bill into law. The president cannot pick and choose when he deems a Senate session to be “real.”

Seth Borden/ Labor Relations Today / J Smithson/Midknight Review