Citing similar cases in which other national banks violated sanctions against Iran, the lawyers noted that none of the directors of those banks were arrested or sentenced but Atilla, who had no connection with the USA, was facing a prison term.
The transactions violated U.S. Sanctions and were disguised as fraudulent gold and food transactions through Halkbank, prosecutors said.
Turkish President Erdogan has said the U.S. case was based on evidence fabricated by followers of US-based preacher Fetullah Gulen, who Ankara also accuses of carrying out the failed 2016 coup attempt.
Atilla has already served 14 months in prison since his arrest last year during a business trip to New York.That time will be credited toward his sentence, allowing him to return to Turkey in about a year.
Atilla was found guilty on January 3 of conspiring to violate US sanctions law.
Those included Turkish government officials and Turkish-Iranian gold trader Reza Zarrab, who pleaded guilty and testified against Atilla.
During trial a year ago, prosecutors labeled Atilla an "architect" of two schemes to accomplish this.
Zarrab, who has yet to be sentenced, testified during Atilla's trial that he bribed Turkish officials, and that Erdogan personally signed off on parts of the scheme while serving as Turkey's prime minister. As a result of this scheme, he and his co-conspirators caused USA banks to unknowingly process transactions on behalf of the Iranian government, the Justice Department said.
Atilla appeared to be a marginal figure in the case.
The Turkish government has fulminated about Zarrab and Atilla's cases, labeling them an attempted "judicial coup" on Erdogan. Atilla, by contrast, wasn't named as a defendant until nearly a year after the indictment was unsealed.
Though nine people were charged, including Aslan and Turkey's former economic minister, Mehmet Zafer Caglayan, the others managed to evade US custody and haven't faced trial.
Berman said the lengthier prison terms recommended would be "inappropriate, unreasonable and unfair".
Turkish government officials vilified the participants in the USA court proceedings, with the state news media labeling Berman, prosecutors and even reporters pawns in an elaborate conspiracy by Islamic preacher Fethullah Gulen, a former Erdogan ally turned state enemy.
"This is the biggest sanctions-evasion case prosecuted in the United States that we're aware of", Lockard said, sounding dispirited by the judge's opening remarks.
Judge Berman did not contest the gravity of the sanctions evasion plot.
"If Hakan Atilla is going to be declared a criminal, that would be nearly equivalent to declaring the Turkish Republic a criminal", he said.
"This is something of an exceptional sentencing proceeding", U.S. District Judge Richard Berman said as the three-hour hearing kicked off this morning.