Arlington County’s police chief has acknowledged a pattern of internal memos dating back years that direct officers to make a minimum number of arrests and issue a certain number of traffic citations each month.

Chief M. Douglas Scott said that the memos did not amount to a quota system but that they could be interpreted that way. He has called quotas “professionally unsound” and has since directed his staff not to issue quotas or anything resembling them.

Scott was prompted to look at past memos to patrol staff after he rescinded a similar memo last month that threatened discipline for those who didn’t make enough arrests or write enough tickets. When he read older memos, he said, he learned that the practice was years old.

Scott is dealing with an issue that police chiefs across the nation grapple with as they work to give officers guidance without pushing them into arrests and ticket-writing.

“There’s a very fine line between holding officers accountable and setting quotas,” said Chuck Wexler, executive director of the Police Executive Research Forum. “You want to stop short of setting quotas. You never want to put that kind of pressure of officers.”

Scott said he first saw the March 1 memo, written by two patrol commanders, when news media reported it. But his deputy chief of the Operations Division, Michael Dunne, was included in late February e-mail discussions about the productivity memo before it was issued, according to internal documents obtained by The Washington Post.

Another document shows that officers in an off-duty radar enforcement program were required to write five speeding tickets per hour.

Scott said that once he saw the March 1 memo, he “was surprised it was as specific as it was.”

He said that when he looked back, he found similar memos that squad captains had sent to their officers going back several years and that he thinks the practice predates his nine years as chief.

The earlier memos did not mention disciplinary action.

One internal document, dated Oct. 10, 2010, said a “recommended level” of monthly production included one DUI arrest, seven arrests, five field observation reports, five parking tickets and 11 / 2 traffic tickets for each day worked — with no more than 25 percent of them warnings.

“If I had seen this in October 2010, I would have said this is close to a quota system,” Scott said in a recent interview.

He said he had not seen the memos before because he generally does not review memos that squad captains write to their officers. Had he seen them, he said, he would have stopped them.

“I was told we’ve always done it like this,” he said. “The commanders saw it as guidance.”

He has since directed his staff not to write such specific memos and instead to offer a general range for guidance. For example, he said that instead of directing officers to write 15 traffic tickets a month, he would recommend writing between 10 and 30.

“People understand ranges better,” he said. “Police officers are used to having some expectations of what their productivity should be.”

He added that he has never disciplined an officer for not meeting an expected number of arrests or tickets.

Scott said the numbers detailed in the March memo are “not difficult” to hit.

“The high majority of officers make those numbers easily,” he said.