Removing secret documents from specially secured rooms violates government policy.
Gonzales' lawyers wrote in their memo there is no evidence the security breach resulted in secret information being viewed or otherwise exposed to anyone who was not authorized.
The classified notes focus on a March 2004 meeting with congressional leaders about a national security program that was about to expire. Efforts to renew the program sparked an intense Bush administration debate that played out at the hospital bedside of then-Attorney General John Ashcroft.
The memo was prepared by Gonzales' legal team as a response to a report being finalized by the Justice Department's inspector general. The report, which could be released as early as Tuesday, is expected to criticize Gonzales' handling of sensitive compartmentalized information, or SCI, according to the memo.
Gonzales agrees with inspector general's findings that his handling of notes and other SCI documents "was not consistent with the department's regulations governing the proper storage and handling of information classified as SCI," concluded the legal team's memo. "Judge Gonzales regrets this lapse."
Sensitive compartmentalized information is one of the highest and most sensitive levels of classified documents and is deemed top secret. It usually relates to national security cases.
Gonzales' lawyers acknowledge that he kept the notes in a safe in his fifth-floor office at the Justice Department, along with a small number of other highly classified papers, instead of in the special facilities accessible only by certain people with top secret security clearances.
He also may have taken the notes home at one point in 2005 as he was moving out of the White House counsel's office, where he served until he was sworn in as attorney general at the start of President Bush's second term, the memo says.
The inspector general's report will be the latest in a series taking Gonzales to task for his management of the Justice Department. He resigned under fire in September 2007. At least two more reports, including one looking at Gonzales' role in the ouster of nine U.S. attorneys, are expected in coming months.