The Obama administration last week urged the Supreme Court to let it apply new laws to old crimes in cases against immigrants who are in the country legally. But that kind of retroactivity would be both unusual and unfair; the court should say no.

The administration made its argument in Vartelas v. Holder, a case that will test whether a provision in a sweeping 1996 immigration law that bars legal immigrants convicted of certain crimes from traveling abroad and then reentering the United States can be applied to people whose crimes were committed before the law was passed. The problem is that Congress never made it explicitly clear that it intended the provision to be applied in that way. To do so _ as immigration officials would like to _ would be absurd.

The case centers on Panagis Vartelas, a green card holder who pleaded guilty in 1994 to a white-collar counterfeiting charge. At that time, Vartelas' conviction was not a deportable offense, nor did it bar him from briefly traveling abroad. In 2003, Vartelas made a quick trip to Greece to visit his parents. When he returned, however, he discovered that his old guilty plea had triggered an additional penalty _ he was barred from reentering the United States under the 1996 law. He fought the decision and was allowed to return to New York while the case continues. He has spent the last eight years battling to stay in the country.

The court should reject the government's push to deport Vartelas and other similarly situated immigrants because it is an unreasonable attempt to impose new rules on old acts. When Vartelas pleaded guilty to the counterfeiting charge, he had no way of knowing that that conviction might at some future date get him tossed out of the country. How could he? And if he had known, he might have considered changing his plea.

The Constitution prohibits placing new penalties on old acts in criminal cases; "ex post facto" laws are banned in Article I. And while the rules are less clear in civil matters, including immigration cases, the courts have set very strict limits on when and how laws may be applied retroactively, requiring Congress to explicitly state its intent.

This isn't the first time federal officials have been forced to defend the 1996 immigration law. In 2001, the Supreme Court struck down another provision that sought to apply retroactive sanctions. Justice John Paul Stevens, writing for the majority, wisely noted that such attempts contradict a long tradition of American jurisprudence against making laws that apply to past acts. We hope Steven's words are heeded again by the high court.

— Jan. 20, Los Angeles Times