About two weeks ago, Montgomery County School Superintendent Charles M. Bernardo suggested that student government leaders could help end the spate of drug arrests in the county schools by exerting "peer pressure" on their fellow-students and persuading them to stop smoking marijuana.

Yesterday, the student government leaders said they had a better plan for stopping the arrests; the state, they said, should decriminalize marijuana use.

"For millions of young people who are defined as criminals under the current marijuana laws, these laws only increase their disrespect and bitterness for the entire legal system," said John Heilprin, a junior at Walt Whitman High School.

"They resent being defined as criminals in a society which permits, and even encourages through advertising, the use of such proven unhealthy and dangerous drugs as alcohol and tobacco," added Heilprin, who drafted a resolution passed by more than half of the 100 high school delegates assembled for a regular meeting yesterday.

The resolution, however, said that students who smoke marijuana on school grounds or during school hours should be subject to the same severe school penalties that now cover students who drink alcohol at school.

As the students were convening, however, Montgomery County police officers were arresting eight young people on drug charges. The arrests at three high schools brought to 139 the number of young people arrested since the police began cracking down on drug use at county schools last month.

Yesterday, two Gaithersburg High School students and three Sherwood High School students were arrested and charged with possession of marijuana. Three others were charged with possession of PCP.

Charged with possession of PCP are 19-year-old Gerald Garland Weaver, 8701 Woodfield Ct., Gaithersburg; a 17-year-old student at Damascus High School, and a 17-year-old girl who recently graduated from Damascus High School.

The three were arrested in a car near Damascus, where police followed them after allegedly spotting the three using drugs in the school parking lot. The 17-year-old girl also was charged with concealing a deadly weapon. Police said she had a sawed-off shotgun, a .22 automatic rifle and a 16-gauge shotgun. The weapons were not registered.

Yesterday's passage of the decriminalization resolution by the Montgomery County Regional Association of Student Councils proves the way for the Maryland Association of Students Councils to consider the same question at its convention this fall. If the resolution is passed there, the association's legislative council would lobby state legislators to pass a measure to decriminalize marijuana.

But Alan Goldstein, a lawyer for the National Organization for the Reform of Marijuana Laws, said decriminalization of marijuana by a state might not have much effect on juveniles. "The decriminalization bill that we have before the legislature has always been limited to the statute that affects adults," he said. "It would make possession of marijuana a civil infraction like a parking violation. Juveniles might still be brought before juvenile court."

In another resolution, passed yesterday, students said that drugs should not be used on school grounds, even if marijuana is eventually decriminalized. They called use of drugs during school hours a source of "concern and abhorrence."

But they asked for an end to "police-initiated" arrests of students using drugs until student delegates meet school officials and police to discuss alternate ways of curbing drug use during school hours.

In that resolution students also asked for durg education programs for adults as well as students. "Some parents have to learn that smoking marijuana isn't the same as shooting up heroin," Heilprin said.