The Justice Department's Office of Legal Counsel, as I've noted all day, released its opinion on recess appointments and pro forma Senate sessions today. The bottom line: in their opinion, the pro forma gimmick is illegitimate, and the president is free to choose to ignore those sessions and treat periods such as the current one as proper, Constitution-qualifying recesses for the purpose of recess appointments.
First, the substantive implications. OLC basically leaves alone the old three-day minimum; the point here is that situations such as the present one are in fact long (enough) recesses, notwithstanding the pro forma sessions. This opinion does not, as I see it, put the presidency on the path to making recess appointments when the Senate breaks for lunch, or overnight or on weekends. Second, it opposes any use of pro forma sessions to create phony recesses -- while OLC does note that during the current Congress the gimmick has been forced by the House, there's nothing here to hold back a future president faced with the situation that George W. Bush faced (and accepted) in 2007-2008. In my view it would have been sensible to distinguish between a Senate-supported pro forma gimmick and one forced by the House against the preferences of the Senate majority, but there's no support for that view here.
Second, the strength of the opinion. Basically, OLC says that this is a new question (the tactic never really showed up before 2007), that there's very little Constitutional guidance, and that consequently the call could basically go either way, although they argue that the pro-appointment side has the better of it. For a good analysis of this part of it, see Bush-era recess appointment supporter John Ellwood.
Third, while it's true as Matt Glassman points out that an OLC opinion has no force of law and is to be expected to take the point of view of the executive branch, I'd caution against interpreting this purely as a case of the president overriding Congress's claim that they are in recess. Congress per se has made no such claim, and OLC relies not just on previous Justice Department opinions but in several places on what Congress itself has said over the years.
Fourth, ultimately, however, the decision rests (as Adam Serwer says) on the claim that the practical reality of a Congress out of town and in fact not dealing with appointments trumps the claim that Congress is technically still in session during such periods.
My general feeling about this remains the same. I strongly support a meaningful advise-and-consent role for the Senate in the nominations process; in fact, I mostly oppose some of the "streamlining" reform efforts to move large numbers of executive branch positions out of the category of nominations that need confirmation. However, I don't think that recess appointments are much of a threat to the Senate's role. As a presidential weapon, they lack punch. On judicial nominations, recess appointments are massive surrenders for the president since they involve trading a lifetime slot for a short-term one. And even in the executive branch, recess appointments have real disadvantages over regular confirmed nominations. Recess appointments at best are a weapon for presidents to use in negotiating with the Senate, not a potential replacement for it.
And as for the specific question...again, as a non-lawyer, my sense is that it's a close call if the majority of the Senate insists that they are not in recess while the president believes that they are for all practical purposes, but that it's a much less close case when the majority of the Senate agrees with the president and only the House (and the Senate minority) disagree.
Of course, there is something that the president and the majority of the Senate could do other than recess appointments: they could reform the Senate to allow for majority confirmation of executive branch nominees.