Let us be merciful as well as just.

-- Henry Wadsworth Longfellow, "Tales of a Wayside Inn"

When addressing the mess that is U.S. immigration policy, the new Congress must consider whether to extend mercy to unauthorized immigrants, or just punish them.

Some Americans fear that we already have too many people who don't look, sound, or act "like us." They argue that forgiving unlawful entry or unauthorized presence is bad policy, undermining the general principle that laws should be obeyed and violations punished.

America, however, has a long history of forgiving violations, for a variety of reasons. Amnesties often arise in the context of minor infractions, such as parking tickets and library fines or, sometimes, failure to pay taxes. Bankruptcy law is all about forgiving debts. From the Vietnam-era draft dodger amnesty to presidential pardons, our country has often forgiven those who have done wrong.

Although the anti-immigrant crowd argues otherwise, amnesty is not only an acceptable concept; it runs throughout our history.

Over these holidays, we should also remember that mercy springs from our most prevalent religious traditions. The name by which God revealed himself to Moses was "The Lord GOD, compassionate and gracious." (Ex. 34:5) Christmas is about God's gift of a son who embodied forgiveness for a guilty world. Muslims pray five times daily "in the name of Allah, the most Compassionate, the most Merciful."

Presidents and governors often pardon criminals whose original moral culpability is questionable. Couldn't we consider doing that for young illegal aliens whose only fault is that they accompanied their parents to the United States when they were children, and who now know no country but this one?

Clemency sometimes comes as a reduced penalty, replacing one that society concludes was too harsh. Current law banishes for 10 years from family, education and work those who have stayed illegally at least one year; could we consider replacing that penalty with a substantial fine?

Society has reconsidered punishments, especially, when it collectively realizes that the law violated was itself, perhaps, wrong-headed. Is it too much to hope that America will see that its efforts to restrict the labor supply for a booming economy through rigid immigration quotas was a mistake, and that those who came here, notwithstanding that law, to do honest hard work should get a pass?

Amnesty is never an entitlement. In general, law should be enforced and violators punished. But not always. American immigration law provides many good exceptions to that general rule.

The problem of 12 million or so unauthorized residents in our country is the single most difficult part of fixing a broken immigration system. With enough time, money and determination, we could theoretically expel all of them. The consequences for our economy and for families left behind, however, would be grave.

In circumstances like these, thinking ahead argues strongest for mercy. As Dutch botanist Paul Boese said, "Forgiveness does not change the past, but it does enlarge the future."

(Hans Christian Linnartz teaches immigration law at Duke Law School and practices law in Durham.)