The United States on Tuesday quietly deported an Iranian arms dealer back to Iran. The man was snagged in a controversial 2007 Immigration and Customs Enforcement sting that some lawyers contend set up a disturbing legal precedent.

If the United States can accuse an Iranian inside Iran of breaking U.S. law, abduct and jail him, can Iran then accuse Americans inside the United States of breaking Iranian law, abduct and jail them? That's the issue the case raises.

In all, Amir Hossein Ardebili, served four-and-a-half years in U.S. federal prison, including more than two years during which he was held in secret—a move that stirred controversy.

Ardebili "completed serving his prison sentence last month and was turned over to ICE for deportation," Justice Department spokesman Dean Boyd told Yahoo News by email Wednesday. "Whenever a foreign national is convicted/pleads guilty to federal crimes and completes his or her prison term, they are typically then turned over to ICE for deportation from the U.S."

Ardebili, 38, an Iranian procurement agent from Shiraz, was lured to the former Soviet state of Georgia by Immigrations and Customs Enforcement agents in 2007 in a sting targeting illegal Iranian imports of western defense technology.

Deported to the United States, Ardebili was held in secret for 22 months before the Justice Department revealed the case against him ahead of his sentencing hearing in December 2009. Ardebili was sentenced to five years in prison, including time served, after pleading guilty to having attempted to purchase "restricted military-grade radar, gyroscopes and cockpit computers deployed in the F-4 fighter jet," Reuters writes.

On Tuesday, Ardebili was escorted by U.S. agents to "Europe, where he was scheduled to catch a KLM flight to Tehran," Reuters writes. "Two U.S. officials briefed on the matter said that Ardebili's deportation moved with unusual swiftness."

There's "nothing unusual" in Ardebili's swift deportation, the Justice Department's Boyd said.

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But some observers of the case wondered if his swift transfer to Iran is meant to facilitate the release of a former U.S. Marine currently being held by Iran on spy charges. Iranian authorities announced this month that they had overturned a death sentence for the former U.S. Marine, Amir Hekmati, 28, of Flint, Michigan, and were ordering a retrial.

And then there's the potential legal angle.

"What would be the response if Iranian agents abducted the CEO of Twitter while he was in, say, the UAE, dumped him into solitary confinement in an Iranian prison, and secretly indicted him with aiding and abetting sedition by Iranian dissenters?" Clif Burns, an export control attorney with Bryan Cave, told this reporter when Ardebili was sentenced in 2009.

"The U.S. government and the general U.S. population would be apoplectic," Burns said.

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