In waging the war on drugs, police nationwide have long faced an implicit hazard: the life-threatening danger of stalking drug dealers on darkened city streets.

But police departments increasingly are confronting a more insidious threat in battling drugs, law enforcement experts say, one that could undermine their own integrity.

Their own police officers may be the local drug addicts -- or the local drug dealers.

"Drugs" said Hubert Williams, the president of the Police Foundation in Washington, "are definitely a problem which police departments are experiencing across the country."

Those few officers who in the past would succumb to protecting the neighborhood bookmaker might now be protecting the neighborhood drug dealer.

And the ranks of corrupt police officers who extort drugs for their own profit have been joined by those who extort drugs to support their own addiction.

"The combination of substance abuse plus corruption is new," said Edith Flynn, a professor of criminal justice at Northeastern University. "But at this point in time, it's also growing in major urban areas."

In Massachusetts, two former Lawrence police officers were indicted last week on charges that they had extorted Cocaine and money from dealers in exchange for protecting them or aiding their drug dealing. The two former officers, Fausto D. Ruiz and Daniel N. Fillipon, are accused of conspiring to help four drug dealers distribute Cocaine as well as extorting money and Cocaine from them in exchange for assistance that ranged from free ammunition to altering police records.

While the criminal charges against Ruiz and Fillipon do not identify them as drug users, sources close to the investigation have said that the officers did use cocaine. They even may have sought treatment for addiction, a source said.

The indictment was the first that law enforcement authorities could remember in Massachusetts in which drug addiction and corruption may have combined. More common are cases in which drugs and corruption combine for profit. But New York, Miami and other cities are believed to have had a few cases of corruption and addiction.

In recent months in New York City, for example, six current or former police officers have been accused of robbing an undercover officer and stealing from drug dealers. Officials have said drug abuse is believed to be a motive.

Criminal justice and police corruption experts are quick to note that those police officers who use drugs are in the minority and that drug abuse does not necessarily lead to corruption.

Nor is drug abuse a problem unique to the police force: It cuts a wide swath through professions ranging from law to medicine. "The first question is, do we think drug use is more common in police departments than in other organizations? I suspect not," said Mark Moore, a professor of criminal justice at Harvard University's Kennedy School of Government.

"The point is, for many police officers it is their official position that should keep them from using drugs."

But drug abuse and police corruption can coincide. And the roots of drug-related corruption lie as much in the nature of the 1980s as in the shifting faces of police forces.

Unlike their predecessors on the force, officers in their 20s and 30s grew up in the heady days of the late '60s and early '70s, when drug use was sometimes considered a badge of distinction.

"Thirty years ago, when I was a young police officer, we came out of blue-collar backgrounds where cards, dice and horses were a fact of life. It wasn't surprising that some police officers made arrangements with some of the gamblers," said Thomas Reppetto, a former police officer and now the head of the Citizens Crime Commission in New York City.

"Today, you have a young generation that grew up in a drug permissive society. . . . They get set down in the middle of precincts with wide-open drug sales and teen-agers making thousands of dollars. A certain number are going to succumb."

Williams, of the Police Foundation, said: "The question for police recruits isn't whether they have used drugs but whether have serious problem with drugs. That was never an issue before."

The particular pressures of police work -- not to mention the demands of fighting the drug war -- can culminate in an officer turning to drugs.

But some officers used drugs long before they joined the force, argue law enforcement authorities.

A source close to the Lawrence investigation, noting that the officers were under 40, said: "Younger people like these got involved with it socially first." He added: "Younger cops try to get away from the stereotypical situation where police officers socialize with police officers. They overlap with a society where drug use is not a big thing."

The numbing disillusionment of fighting drug dealing also plays a role, authorities say, as does social tolerance of drug abuse. As dealers revolve in and and out of jails, as famous athletes go unpunished for abusing drugs, police officers begin to wonder why they should be any different.

Others become caught in a web of drug-related corruption through the informants they develop.

"You're giving informants narcotics for them to make good cases on other people. Pretty soon you are financing the sale of narcotics," said Robert Leuci, a former police officer whose own experiences with that kind of corruption led to his book "Prince of the City."

But most criminal justice and police experts agree that one of the roots of the problem of drug abuse and corruption lies in the recruitment of police officers themselves. As more and more forces struggle to find new recruits, they have failed to take drug abuse into consideration.

"When there was an effort to enlarge a police force, there was not sufficient screening of police officers," said Flynn, the Northeastern professor.

Flynn contends that as departments have reached beyond the working class, from which police recruits typically hail, they have recruited officers without a working-class, law-abiding attitude.

"There isn't enough grounding, enough ideology, to be law-abiding," Flynn said.

Not that police departments are not now taking drug abuse into consideration as rookies join the force. Hotly debated by many police authorities now is whether departments should have mandatory drug testing of new recruits.

"Many police executives are now wondering how you should look for and respond to drug abuse in police forces," said Harvard's Moore.

Experts say that under current law, a police officer cannot be tested for drug use unless there is a reasonable suspicion involved with drug-related activity.

But police corruption authorities and many police chiefs would probably argue that the best solution is the most bitter medicine: the identification and prosecution of officers who become corrupt and abuse drugs.

Several experts interviewed hailed the indictments in Lawrence, particularly since they resulted from an investigation begun by the Lawrence police force. Only by setting an example for other police officers can corruption be curbed, they contend.

"Sometimes police departments take a different approach. They don't want the public embarrassment of having an officer arrested as a junkie," said Williams. "But when these incidents occur, good police departments and effective police departments should jump on them immediately."