Over the summer, lawyers for the Treasury Department had discussions with the National Security Division about whether — or at what stage — that process should count as a “proceeding” that falls under the disclosure provision, according to officials who spoke on the condition of anonymity to discuss internal deliberations.

When designating groups for sanctions, the Treasury Department announces its decision without notice. The designated groups can request that it reconsider; if that effort fails, they can file a lawsuit. Neither the designated groups nor their lawyers get to see any classified evidence against them, but at the lawsuit stage a judge is shown that information.

Erich C. Ferrari, a lawyer who represents foreign clients who have challenged their designations by the Treasury Department, said the government typically provided very little information about the basis for its decisions. He argued that “the language of the statute should control” its interpretation and said he considered even the administrative reconsideration stage to be a “proceeding.” He added, “I think they would try to find a way to get out of that.”

Jimmy Gurule, a Notre Dame law professor who served from 2001 to 2003 as the Treasury Department’s under secretary for enforcement, a post that oversees the Office of Foreign Assets Control, said there was a strong argument that every stage of the process be counted as a “proceeding” because the statute was written broadly, meaning that the FISA notice law should apply from the start.

There is also precedent for the Treasury Department’s providing notice after a group has received its designation and is trying to have it reconsidered. In 2007, after an Ohio-based charity accused of funding Hamas asked to have its assets unfrozen, Treasury told the group that it was relying on FISA evidence for its designation, court papers show. But that case involved a FISA warrant targeting an entity on American soil.

The Treasury Department declined to explain how it has decided to interpret its obligations under the disclosure rule, although it provided a general statement.

“The Office of Foreign Assets Control is committed to complying fully with FISA, which we implement in close consultation and collaboration with the Department of Justice,” it said. “We are confident in the legality and validity of our designation actions, including decisions taken in response to delisting requests.”