The Supreme Court of the United States refused to rule on whether the Line Item Veto Act of 1996 violated the Constitutional separation of powers by impermissibly delegating legislative powers to the President because the Congressmen who brought the suit did not have standing to maintain the action.
Raines v. Byrd, 117 S. Ct. 2312 (1997).
Michael J. Cremonese,
Constitutional Law - Standing - Separation of Powers,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol36/iss4/10