Speaker Pelosi told a group of liberal bloggers that she would sue the President over signing statements and his veto. In response, I found the article below.

"In short, under existing jurisprudence in the D.C. Circuit, I don't think legislators would have standing in the scenario outlined earlier. But I think a larger point is in order. It seems to me that law suits by members of Congress against the President or other members of the Executive Branch where those members of Congress claim an institutional injury are precisely the kinds of disputes that courts should not handle. In other words, I don't think legislators should ever have standing to sue for claims of institutional injury."

FULLTEXT: http://explore.georgetown.edu/blogs/?id=24946