Lawyers at the U.S. Department of Justice (DOJ) concede that substantive errors were made in the legal challenge to President Obama’s executive immigration action.

The errors include inaccurate information disclosed by DOJ lawyers in the early stages of the challenge brought by 26 states to a U.S. Department of Homeland Security (DHS) order extending work permits and renewable legal status to four million undocumented immigrants. Government lawyers told U.S. District Court Judge Andrew Hanen late in 2014 that they would not begin granting deportation deferrals under the program until February 2015 — in fact, the Department issued 100,000 deferrals beginning in November 2014.

Hanen was apoplectic when the deferrals were disclosed, accusing DHS of brazen obstruction and ordering thousands of government lawyers to undergo ethics training. (RELATED: DOJ Defies Federal Judge To Protect White House’s Amnesty)

In court filings released Monday, the DOJ denied intentionally misleading the court, but concede it made a serious mistake.

“We do not dispute that we made mistakes that led to unfortunate circumstances here: at critical times we provided incomplete information to the Court because of our failure to appreciate the scope of the questions asked of us; and we used imprecise terminology in our oral and written submissions to the Court,” the brief reads.

“As a result, our submissions left the Court with an incorrect understanding of the facts regarding grants by the Department of Homeland Security (‘DHS’) of three-year terms of deferred action to individuals qualifying under the 2012 Deferred Action for Childhood Arrival (‘DACA’) eligibility criteria,” it continues. “We acknowledge and apologize for these mistakes, and for the valuable time the Court has expended on this matter as a result.”

In an attempt to appease Hanen, all attorneys in the DOJ’s Civil Division will sit for a one hour training course in ethics and professional responsibility, announced Principal Deputy Assistant Attorney General Benjamin Mizer.

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