Law students encounter early the Holmesian Bad Man — the reason a legal system cannot be based on the fact that most people do the right thing. A legal system must account for the Bad Man, the unusual one who will exploit the system. A legal system must therefore not simply exhort the Good Man to keep doing good but make the Bad Man afraid to do bad. A legal system that fails to make the Bad Man afraid to do bad is doomed.

“A man who cares nothing for an ethical rule which is believed and practiced by his neighbors is likely nevertheless to care a good deal to avoid being made to pay money, and will want to keep out of jail if he can.” The Path of the Law, Oliver Wendell Holmes, Jr., 10 Harvard Law Review 457 (1897).

It is a basic axiom in law, so why not in foreign policy? Why not make bad regimes afraid to do bad?

Objections multiply: foreign policy is the art of the possible; foreign policy contends with different legal systems; foreign policy has to do with making friends and jockeying for position; foreign policy has no moral compass but aims instead to maximize our influence . . . and so on.

The most convincing objection is this: we do not control foreign governments; we have no sovereign power to put foreign bad people in jail for bad acts.  But to this, and all of the foregoing moral abdications about foreign policy, it may still be asked, is it not preferable to make the Bad Man afraid to do bad? Even granting the absence of a moral compass in foreign policy, doesn’t it still make realpolitik sense to signal to the Bad Man that there will be consequences for his bad behavior?  Isn’t this rudimentary poker?

These questions have vital significance in the war on terror. Every rational person agrees that terror — wanton and random slaughter of innocents — is bad. The question in this country has been whether we should prosecute the war against terrorists as a military or a legal proposition.

Proposing that the war on terror should be legal — not military — as John Kerry did in 2004 and Barack Obama did in 2008, supposes that a legal prosecution of the war would have different consequences than a military prosecution, or that it would be more civilized or humane.  It would not.  It would simply cripple our war effort.

Prosecuting the war on terror as a legal, rather than military, proposition ensures the following signals and consequences:

• As everyone is presumed innocent — because our legal system tolerates the guilty going free much more readily than the innocent getting convicted — terrorism may or may not have consequences (indeed, presumptively will not), and the multiple opportunities to obfuscate, to engender reasonable doubt, increase the likelihood that terrorism not only will have no consequence — but will have the globally significant consequence of acquittal.

• Evidence of guilt that has perfect reliability in every respect except the manner in which it was obtained will be suppressed, again increasing the likelihood that terrorism not only will have no consequence — but will have the globally significant consequence of acquittal.

• Bad acts will be viewed in tiresome context, and with relentless due regard to culture and history. Any instance of a bad act must be given a thorough vetting in which the bad actor’s grievance is accorded more privilege of expression than the accuser’s.

• Bad actors must be rounded up one by one and cumbersomely prosecuted within a resource-strained system.

• Bad actors must be accorded a range of rights they would never grant to dissidents in the countries they celebrate — not in itself an objection, just a basis to ask any terrorist defendant, is this right a right you support for others, or only yourself?

• Some bad actors will get off on technicalities, as has already been the case — further emboldening bad actors who witness the ways of exploiting our system.

• Instead of being unceremoniously killed on the field of battle, bad actors navigating the legal system will become heroes.  Indeed, even terrorists duly convicted in the legal system and incarcerated are likely, eventually, to be released and return home to heroic welcome — as with the murderous mastermind of the Pan Am 103 bombing that killed 270 people.

The military solution, unlike the legal solution, attracts jihadists to the military field of combat. Advantageously, jihadists then do war with our soldiers, men and women trained to do battle, as opposed to men and women and children who have no idea they have been targeted for murder.

To his discredit, President Obama and Attorney General Eric Holder continue to speak of the war on terror, without actually using that incendiary language, as though it must be legal.  To his credit, President Obama has blessed a surge, beyond even the ambitions of the Bush years, of military options such as drone missile strikes and CIA-trained Afghan forces operating in Pakistan.  President Obama has plainly learned something in office that he’s unwilling to speak forthrightly about to his base.  If he did, the war on terror could again become bipartisan.

In both the legal and military paradigm for combating terrorism, theoretically, we resolve to make the Bad Man afraid to do bad. But in the military paradigm, we actually make the Bad Man afraid to do bad. In the legal paradigm, we actually embolden him.

Kendrick Macdowell is a lawyer and writer in Washington, D.C.