New York ? Cover 2 has long been a popular defensive scheme in the NFL. Soon, officiating crews might have their own version.

The NFL is experimenting with an eighth on-field official during a dozen preseason games. A deep judge, stationed in the middle of the field behind the secondary, also was used in eight exhibition games in 2010. There is no timetable for making the position a permanent part of current officiating crews.

Pro football has not added an on-field official since 1978, when the NFL was a run-oriented league. Now it has more passing plays than runs, and there is some thought another official would enhance a crew’s ability to call games.

An additional official — there currently are seven on the field and two handling replay in each crew — would need to be approved by ownership.

“Our charge from the commissioner is to innovate,” said NFL officiating director Carl Johnson. “After the 2009 season, we came up with the idea of trying this in the preseason. We’ll take the data we gather and video and input from the coaches and officials and determine if it is effective to help us get better. Will it make us more accurate and be able to call plays better in the passing game, running game, kicking game?”

In the 33 years since on-field crews went to seven — referee, umpire, side judge, field judge, head linesman, back judge and line judge — the speed of the game has increased exponentially. The rulebook also has grown.

With slow motion instant replay, second-guessing of calls has increased, too. The biggest innovation in NFL officiating pretty much has been the coaches’ challenge system.

Last season, there were 361 replay reviews — 252 of them from coaches’ challenges — with 133 total reversals.

The league’s competition committee will review information from the experiment before determining whether to propose adding a deep judge for all games. Obviously, that would add the cost of another 17 employees, one for each officiating crew.

“Our primary concern is the integrity of the game,” said NFL executive vice president for football operations Ray Anderson, a member of the competition committee. “If we can determine adding an eight official makes the quality of the game better, we will make the investment to do that.”

Anderson added that making the deep judge permanent “could happen next season,” but nothing is certain at this point.

With an eighth official, the field is divided into quadrants, with the side judge and field judge in similar positions to where cornerbacks would be in a Cover 2 alignment. The back judge and deep judge would set up behind where the safeties play.

Because the back judge and deep judge could handle the deep middle of the field, the side judge and field judge can concentrate on the outside receivers and who is covering them. The head linesman and line judge would have charge of outside line play, mainly tackles and blocking tight ends going against defensive ends and linebackers. The umpire — now stationed in the backfield on most plays, a switch made for safety before the 2010 season — would handle the interior line, freeing the referee to concentrate on the backfield, particularly watching quarterbacks and pass rushers.

For the 12 preseason games using the deep judge, the league has either doubled up assignments for some officials or used ones whose crew was not scheduled to work that weekend. During the season, every crew gets one week off.

Johnson insists “our intent is not for there to be more flags. It is to look at ways to enhance accuracy” in officiating.