A consistent theme running through the debate over the Iran agreement is that for this deal to work, Iran must be deterred from cheating while its enrichment program is severely restricted over the next 10 to 15 years. After that, Iran must be deterred from producing highly enriched uranium for a nuclear weapon once some — but not all — of the restrictions on enrichment sunset.

For many, the ingredients for effectively deterring Iran already exist — and will be strengthened by this agreement. The deal's provisions for monitoring Iran's nuclear commitments, "snapback" sanctions if Iran cheats and an enduring commitment by President Obama (and, inevitably, his successors) that Iran will never be allowed to obtain a nuclear weapon — coupled with a U.S. military capability that in the words of Defense Secretary Ashton Carter "put no target out of reach" — should give sufficient pause to Iran.

But for others, Congress needs to get in this game and adopt a resolution or legislation that would preauthorize the use of force against Iran if Tehran were to violate the agreement or proceed to enrich uranium past a certain level. Political leavening needs to be brought in to this important policy debate now — along with a sober assessment of the legal and practical implications for preauthorizing the use of force against Iran.

Politically, the notion of Congress preauthorizing the use of force to respond to Iranian violations of the agreement — giving this or a future president a green light to use force against Iran, at whatever level he or she may see fit, in whatever context may arise — should be met with severe skepticism by Democratic and Republican members intent on preserving congressional prerogatives. Moreover, one would suspect that Obama — who made his way onto the national stage in 2002 by opposing the congressional joint resolution authorizing the use of force in Iraq — would oppose adopting such a template for Iran.

Legally, we have a framework for the use of force — that is, the Constitution and the congressional authorization and appropriation process. That legal framework is undermined by a preauthorization of the use of force. Congressional oversight of the use of our armed forces in major combat operations should include a demanding review of the proposed mission and execution plan and of the regional and strategic implications of the aftereffects of using force.

A broad preauthorization abdicates congressional responsibility to consider the facts at the time force is being proposed. For example, there will be compliance issues with this agreement — that is why the agreement establishes a joint commission to deal with these issues as they arise. At what point in this process would force be preauthorized? Would the use of force be preauthorized in advance of, or during, the implementation of "snapback" sanctions? Would that determination require any buy-in by other parties to the agreement — which include three NATO allies and the European Union? Would it require any additional congressional action? Would it ultimately compel the president to use force against Iran? Congress can put itself firmly on record regarding the unacceptability of Iran's acquiring a nuclear weapon, without trying to address — or duck — these issues prematurely.

In light of the political, legal and practical issues, why would Obama seek to engage Congress in a preauthorization resolution negotiation that at the end of the day could restrict his or his predecessors existing freedom of action? Why would Congress agree to write any president — this one or the next — a blank check for the use of force in the most volatile region in the globe? If the answer is to get the deal's critics to back off and to provide political cover for members to vote for the deal, then we are riding a lame pony to a horse trade. Both the buyer and seller are at risk.

There are many ways the administration and Congress can show resolve vis-à-vis Iran, consistent with the president's constitutional authority as commander in chief and Congress' authority in appropriating funds that would accompany the use of force. And we should not underestimate the impression we can make on Iran through the deployment and exercising of our military and the strengthening of U.S. allies in the region. A congressionally preauthorized red line for the use of force in Iran is a bad idea that should be opposed by both supporters and opponents of the agreement.

Steve Andreasen, the director for defense policy and arms control on the White House National Security Council staff from 1993 to 2001, is a consultant to the Nuclear Threat Initiative in Washington, D.C., and teaches at the University of Minnesota's Humphrey School of Public Affairs.