ANSWER: I think the decision is more defensible on the ground that the injury was not sufficiently concrete (too abstract) than on the ground it was too dispersed (not sufficiently particularized). The Senators' claim was that their voting strength on bills subject to the LVA was diluted to some degree, as the LVA decreased their leverage over the President vis-a-vis his preferences. It is not hard to see that this lacks much concreteness. You describe the LVA as rendering their votes "partially ineffective," but that is debatable. Consider this: the budget bill at issue in Clinton v. New York contained more than 2,000 pages, and the President line-item vetoed two lines. To what degree did the LVA really affect Senator Byrd's voting power in the Senate? Consider also that the LVA only applied to certain sorts of bills, and certain line items within those bills. I think all of this suggests that the injury being alleged was somewhat conjectural, and somewhat abstract. (Of course, as your last sentence suggests, the vote was 5-4, so it obviously was not clear.)
QUESTION: I had a question concerning your model outline/answer #3 for Section 901 on the 2010 exam. Could you explain a little bit more about this one? While I understand that it's not the same as Clinton v. NY because the law would have already gone through presentment procedures, I'm confused on how Congress can basically allow the President to choose whether or not to enforce the law at all or in part. Is Congress really allowed to basically say to the President/executive "do whatever you think best"? Is that what you meant by the "delegation in subsection (a) might violate the non-delegation doctrine"?
ANSWER: Yes, I think that gets the gist of it. There is certainly nothing unconstitutional per se in Congress delegating discretion in the enforcement of federal law to the Executive Branch. Indeed, such delegations are inherent in any law, as no law is so clear as to preclude any discretion in enforcement. Typically, that discretion is in the form of how to enforce a statute. But there is no reason it does not also extend to whether to enforce a statute, or at least a portion thereof. In fact, it is unclear we could draw a clear distinction between the two. Consider federal criminal laws. If the Attorney General (or someone lower in DOJ) decides not to prosecute a particular individual (even though there might exist sufficient evidence to obtain a conviction), is that an exercise of discretion as to how to enforce the statute? Or is it discretion as to whether to enforce the statute? The larger point is that there is nothing inherently problematic in Congress delegating discretion in enforcement to the Executive Branch. The relevant question in such circumstances is whether the delegation is too broad, meaning that Congress has failed to provide an "intelligible principle" to guide the executive's enforcement or implementation of the law.