In Lisa Miller¡¦s neighborhood, it¡¦s not uncommon to spot prostitutes working the streets or to see johns trolling for a girl.

That much didn¡¦t surprise her. But she was shocked when, walking one day near her home at Madison and Kedzie, a man pulled up with his window down and propositioned her for sex.

¡§¡¦Do you date?¡¦ That¡¦s what they say,¡¨ said Miller, 44, a mother of three teenagers. ¡§And I¡¦m an older woman. If they¡¦re doing that to me, imagine what they¡¦re doing to the younger girls?¡¨

Residents and business owners in West Garfield Park have dealt with issues like this for years, says 28th Ward Ald. Jason Ervin, and they¡¦re sick of it.

¡§I¡¦ve lived on the West Side of Chicago most of my life É and everybody knows to go to Madison Street to find a young lady,¡¨ Ervin, 36, said. ¡§That¡¦s not a reputation that I want the West Garfield community to have. We want to clean up that scourge.¡¨

Ervin introduced a new ordinance earlier this month that he says will help combat prostitution by creating ¡§prostitution-free zones.¡¨ Under the proposed law, people who are convicted of prostitution would be banned from parks and ¡§public walkways¡¨ within the zones for one year.

But some prostitution advocates say the law could be unconstitutional and set back the recovery chances of prostitutes, whom they view as victims rather than perpetrators of crime.

After hearing complaints about prostitution at a recent neighborhood meeting, Ervin said he decided to propose the zones, a strategy he used as village manager of Maywood.

If passed, the local ordinance will designate a roughly four-by-eight-block areaÑbounded by Jackson Boulevard to the south, Kinzie Street to the north, Cicero Avenue to the east and Kostner Avenue to the westÑas the first zone, Ervin said. The police superintendent and Chicago City Council would have the power to add zones or tweak the boundaries.

If a person is found in a zone within a year of a prostitution-related conviction, she is banned from the area for one year. If she is simply arrested but not convicted, she¡¦s banned for 90 days.

Violators could get jail time Ð seven days to a maximum of six months, for a first offense, plus a fine up to $500 and at least 40 hours of community service. A vehicle ¡§used to violate the ordinance¡¨ could be seized, and the owner could be fined $1,000.

But some who work with women in the sex trade say the law would further penalize the victimÑthat is, the prostitute, who often has a long history of abuse, suffers from mental illness and is addicted to drugs.

Barring these women from their own neighborhoods will be disruptive to their recovery and will only push the problem elsewhere, said Daria Mueller, a senior policy analyst with the Chicago Coalition for the Homeless.

¡§It¡¦s a really bad approach,¡¨ Mueller said, adding that the law may be unconstitutional. ¡§It¡¦s basically saying if you have ever been arrested for prostitution, you can¡¦t exist in a particular neighborhood. It doesn¡¦t matter if you live there or work there or shop there Ð you just can¡¦t be there.

Mueller said she hopes to meet with the alderman to discuss alternative strategies, such as targeting johns and pimps, and directing women to services instead of jail. Various versions of prostitution-free zones have been implemented in other cities, including Portland, Ore., and Washington, D.C.

In Portland, Ore., two similar laws were passed in the 1990s. In 1992, the city of 580,000 residents enacted drug-free zones, in which any person arrested for a drug-related crime was automatically ¡§excluded¡¨ from the area for 90 days. The city passed a similar prostitution law three years later.

Exemptions were eventually added so ¡§excluded¡¨ people could enter the zone for work, doctors¡¦ visits or other services. Drug arrests in ¡§drug-free zones¡¨ reportedly decreased as much as 50 percent in the five years after the Portland law was put in effect.

But a series of legal challenges followed, and the city¡¦s mayor declined to re-sign the law in 2007 after data showed that people of color constituted a disproportionate number of ¡§zone¡¨ arrests in the overwhelmingly white city.

Ervin said he is unsure when the proposed ordinance will be called for a vote.