Authorities unveiled a tough new legal tactic Wednesday aimed at keeping gang members - and the drugs they sell - off the streets of Skid Row.

Under a civil lawsuit proposed by the city attorney's office, 80 defendants, most of them gang members, would be barred from the poverty-stricken, 50-block area on the east side of downtown.

The move is aimed at reducing rampant drug sales from gangs that don't live in the district populated by 4,000 homeless or transient people, many of whom are trying to recover from addictions.

"The single biggest criminal threat faced by the residents of this area is the open and notorious drug dealing and violence committed by hardcore gang members and career criminals who actually commute to Skid Row to do their dastardly deeds," City Attorney Carmen Trutanich said at a news conference.

His comments were repeatedly drowned out by about 20 protesters shouting that the area needed more housing, not tougher policing.

The use of gang injunctions is common in Los Angeles, with more than 40 currently in place that typically target gathering or other activities by a single gang in one area. The legal tool is gaining popularity around the country to disrupt gangs.

Bruce Riordan, the city attorney's chief of gang cases, said the Skid Row action marked the first time an injunction was being aimed at multiple gangs. The lawsuit names members of 31 gangs.

Riordan said several gangs cooperate to maximize drug profits and run the drug trade on Skid Row.

If approved by a judge in the coming months, the injunction would give police officers the ability to arrest those named in the injunction if they are found on Skid Row. A defendant could be charged with a misdemeanor and face up to six months in jail.

University of California, Los Angeles law professor Gary Blasi, who has spent two decades researching Skid Row, worried police might use the injunction to target people without probable cause.

"If they start driving around and stopping people because they look like people on the injunction, I would be concerned," he said.

Skid Row crime rates have fallen in recent years, partly due to an increased police presence under the $6 million-a-year Safer City Initiative that put 50 extra officers on the streets.

Still, drug dealing and use remain a persistent problem, with some Skid Row residents openly smoking crack from glass pipes within a block of the area's police station.

Several Skid Row residents gathered Wednesday at a public park where authorities held the news conference announcing the push for the injunction. The voices of public officials were all but inaudible as protesters chanted then shouted "That's a lie!" at various remarks.

Skid Row resident Veronica Bonner said she was angry that money was being spent clamping down on drug dealers when people really needed jobs.

"When you've got no money, you are going to come right back down to these streets," Bonner said.