There were two perfectly predictable schools of thought being expressed after the conviction of Jose Padilla on Thursday on terrorism-related charges. Supporters of the Bush administration said the conviction justified the more than three years Mr. Padilla spent in military detention before his criminal prosecution, while the administration’s opponents said the verdict proved that the criminal justice system should have handled the case in the first place.

But the real innovation in Mr. Padilla’s case, some legal experts said yesterday, was more subtle than those dueling talking points suggested. The Justice Department’s strategy in the trial itself, using a seldom-tested conspiracy law and relatively thin evidence, cemented a new prosecutorial model in terrorism cases.

The central charge against Mr. Padilla was that he conspired to murder, maim and kidnap people in a foreign country. The charge is a serious one, and it can carry a life sentence. But prosecutors needed to prove very little by way of concrete conduct to obtain a conviction under the law.

“There is no need to show any particular violent crime,” said Robert M. Chesney, a law professor at Wake Forest University and the author of a recent law review article on conspiracy charges in terrorism prosecutions. “You don’t have to specify the particular means used to carry out the crime.”