There's a problem with that theory, though. If Congress truly were injured, it could pass a law compelling the president to take the action it wants him to take. That hasn't happened, a point that House Republicans heard yesterday in a hearing on Boehner's lawsuit:
Walter Dellinger, a witness for the Democrats and a former solicitor general under President Bill Clinton, warned of the dangers of creating a federal judiciary that has too much authority to interfere with the executive and legislative branches. And he argued that allowing a lawsuit like Mr. Boehner’s could lead to a situation in which the president could turn around and sue Congress. [....] Mr. Dellinger also noted that the House was pursuing the case on its own, without cooperation from the Senate, which he said undercut the notion that Congress as an institution had been wronged. “In lieu of having a law passed by the House and the Senate saying these new requirements have to take effect,” he said, “the House alone is going into court.”The point is that if Congress feels injured, it has many levers of power other than going to court. The fact that Democrats control the Senate doesn't give Republicans an excuse to sue the president—it undermines the very theory of their lawsuit. Moreover, even without the Senate's cooperation in passing a new law, House Republicans still can force a government shutdown if they want to exercise their power. Of course, they almost certainly won't do that in 2014, because they realize it would be a political disaster for their party, but the fact that exercising their power is politically inconvenient isn't a very convincing rationale for why they should sue the president instead.