Adults who decide to serve alcohol at their teenagers' parties may soon find themselves facing fines or even jail time under an ordinance that Carlsbad's City Council is expected to approve Tuesday.

"We're going forward with the ordinance so the officers have an extra tool in their tool box to curb underage drinking," Carlsbad police Capt. Neil Gallucci said Monday.

The council unanimously gave its initial support to the proposed ordinance last week, and is expected to give final approval at its 6 p.m. meeting Tuesday at City Hall, 1200 Carlsbad Village Drive. If approved, the ordinance would go into effect 30 days later, City Attorney Ronald Ball said.

Carlsbad is one of the last of San Diego County's cities to adopt what's referred to as a "social host" ordinance. Poway went first in 2002, and most other communities in the region had theirs in place by 2008.

The decision for Carlsbad to wait was deliberate ---- city officials said they wanted to see what other towns experienced.

At last week's City Council meeting, Carlsbad's police Chief Tom Zoll said the time has come for Carlsbad to join the others. He said the city recently has seen an increase in teenage drinking issues.

On Monday, Gallucci said that police officers respond to at least one to two complaints about large, loud parties every weekend and many of these events involve teenagers with alcohol.

Under the ordinance, adults who host parties where teenagers consume copious amounts of alcohol could face a fine of up $1,000, or six months in jail, or both jail and a fine, the city attorney said.

Police officers don't have to see an adult hand a teenager a beer in order issue a citation ---- it's enough for the homeowner to be present when the party is occurring and aware that alcohol is being served, Gallucci said.

For example, if there are "15 to 20 kids with beers in their hands" and the adult is in the room, it's an easy call, he said.

Social host ordinances are directed at large parties, not at small family gatherings. While the ordinance makes it illegal for adults to give other people's children alcohol, it is not a crime to give your own children a sip of wine for religious or other reasons, Gallucci noted.

Call staff writer Barbara Henry at 760-901-4072.