Cops are human, and the natural impulse to help a family member can put them in situations in which they're tempted to use their badge or gun in a personal dispute. And that can lead to trouble.

The weekend incident involving Sgt. Frank Tepper is at least the fourth case in the past two years of an officer allegedly abusing his authority in a personal matter.

Department policy in a 1998 memorandum on off-duty conduct is clear: Officers are not to "take action in minor family or neighborhood disputes . . . unless such action is necessary to prevent bodily injury or death."

"In most off-duty situations," the memo says, "the best action an officer can take is be a good witness and call 9-1-1." The memo specifically bars officers from taking any action other than calling 9-1-1 if they are drinking.

The memorandum on off-duty conduct, by then-Commissioner Richard Neal, followed several lawsuits in the 1990s involving officers accused of abusing their authority in personal disputes.

A key case involved two off-duty officers who chased two other men after a taproom altercation and beat them after identifying themselves as police officers.

In a civil suit against the officers, attorney Alan Yatvin introduced a list of 26 cases in which Philadelphia officers had allegedly abused their authority. A federal jury found that the department had failed to properly train, investigate or discipline officers for off-duty misconduct.

Here are three other recent cases of officers accused of intervening in personal disputes:

* In November 2008, Sgt. Chauncey Ellison went looking for some young men in West Oak Lane who had assaulted his 14-year-old son and robbed him of a pizza.

Although he was off duty, Ellison brought his service weapon and allegedly shot Lawrence Allen, 20, who was unarmed. Allen died three months later. Someone else later pleaded guilty to the pizza robbery.

Ellison is now on desk duty, and he and the department have been sued. The District Attorney's Office has not decided whether to charge him in the shooting.

* Officer John Safarowicz was dismissed from the department after an incident in September 2008 in which he allegedly used his badge to gain entrance to a Roxborough home and assault a man who lived there.

According to court documents, Safarowicz was looking for two men who had assaulted his brother-in-law. He has pleaded not guilty and faces trial in March.

* In August 2008, Officer Alberto Lopez was caught on a video surveillance tape storming into a convenience store while on duty to confront four young people who'd been in a minor accident with Lopez's son.

Lopez jammed his gun into a young woman's face hard enough to leave a bruise. He recently pleaded guilty to violating departmental regulations and is awaiting discipline in the case.

The department has no policy about on-duty officers' taking action in cases involving a friend or family member.