D.C. police no longer have the authority to arrest a motorist who disregards an order to stop after running a red light, driving a few miles above the speed limit or committing other minor traffic offenses, under new decriminalization guidelines issued by police yesterday.

Although motorists may no longer be arrested for failing to heed an order to halt after a minor offense, they still are required by law to do so, according to police general counsel Vernon S. Gill. Drivers who stop may be ticketed; those who refuse to stop are subject to be ticketed and fined for both the original offense and for failing to halt, he said.

The guidelines are based on city regulations designed to implement fully the city's two-year-old program of decriminalizing minor traffic offenses . . . meaning that motorists are not subject to arrest for them. While most minor traffic offenses have been made subject to civil fines rather than criminal penalties under the program, yesterday's guidelines appear to be the first formal acknowledgement by police that motorists refusing to stop after minor offenses are not subject to arrest.

Police said that they are seeking to regain the power to arrest motorists who disregard orders to halt after minor infractions and noted at the same time that they retain the power to arrest motorists in more serious infractions and for failing to obey orders to stop after such infractions.

In addition, while acknowledging that the new guidelines may cause confusion, Gill said he expects they will have little immediate effect on public safety or law enforcement practice. Most motorists automatically pull over when asked by police, according to another police official.

The limit on police arrest power comes from a package of new regulations designed to implement descriminalization, which took minor traffic cases out of Superior Court and placed them before Transportation Department hearing examiners. The delay in issuing the regulations called into question the validity of the operation of the system during the last two years and of the penalties and fines already imposed under it.

Although police officials have taken the position that decriminalization went too far, Council member David Clarke (D-Ward 1) said the original legislation, designed to increase efficiency of parking and traffic enforcement and relieve burdens on Superior Court, was proposed by the city's executive branch.

Under instructions issued yesterday, police also were told that they lack the power of arrest to enforce laws against parading without a permit, pedestrian violations and motorists' failure to display upon request a permit and/or registration.

Clarke expressed general sympathy last night with the concept of changing the law to reimpose criminal sanctions for parading without a permit, failure to show registration, and failure to stop when ordered.

While under the new regulations it might be more difficult to identify drivers clearly enough to issue them tickets, Richard Brooks of the police general counsel's office said it would still be possible to get enough information for a citation.

Police are instructed to obtain a description of the car and driver, as well as the vehicle's license tag number. Brooks said the information will be sent to the Department of Motor Vehicles for use in eventually getting a ticket to the driver.

If a motorist refuses to stop after committing a minor offense, such as driving the wrong way on a one-way street, police are instructed to keep the vehicle in view to determine whether other offenses might be committed.

Police retain the authority to stop motorists for more serious offenses, such as reckless driving. The new police instructions advise officers that under some traffic conditions, running a single red light could constitute reckless driving.

In addition to reckless driving, offenses still covered by criminal law include driving more than 30 miles an hour over the posted speed limit, leaving the scene of an accident, drunk driving and acting as a driving instructor without a license to do so.

Brooks pointed out in an interview last night that motorists who see the flashing lights of a police car may take a considerable risk by making the unilateral decision to proceed with impunity.

"You take your choice and take your chance," Brooks said.

Although the process by which a ticket could be issued to a motorist who refuses to halt might appear cumbersome and inefficient, Brooks said police would not abandon efforts to cite violators.

"We'll try to make sure they don't get away with it," the lawyer said.

Many police officers expressed particular concern about the loss of the traffic stop as an investigative tool. In many cases, officers say, stopping an auto being operated in an erratic manner has made it possible to obtain evidence vital to a felony arrest.

One of those expressing concern about the effect of the new regulations was Deputy Police Chief Alfonso Gibson, who said that crimes often are solved as a result of stopping a car for a traffic offense.

The new regulations would not prevent police from stopping a car believed stolen or otherwise involved in crime.