When it comes to protecting citizens from crime, the police are on the front lines. Prosecutors, courts and corrections deal with offenders only after they are apprehended by the police.

So it is both natural and right that the Portland Police Department should be seeking the most effective way to deal with convicted sex offenders once they have been released.

It is difficult for anyone involved, including police, local elected officials and state lawmakers, to determine exactly how to handle those who have “paid their debt to society” and yet may remain unable to resist strong impulses to offend again.

The solution society has found is to monitor their movements and require them to find places to live and work that put some distance between them and those considered vulnerable, specifically children.

How far is far enough? No one knows that, or even whether any distance provides protection, but people in search of solutions when a problem may not have any satisfactory answers will strive to find them nonetheless.

That is why it made sense for the city’s police force to decide that it wants the City Council to focus on where the highest-risk offenders live.

One of the problems with requiring sex offenders to register upon release is that the law casts a very broad net, covering people whose crimes may involve sex between under-age and legally adult teenagers, for example.

Others have offended many times, as opposed to those who only committed one crime decades ago and have remained law-abiding ever since.

Police propose using a point system to evaluate each person’s risk of reoffending, using the results of that to decide who to place under restriction.

There are 170 registered sex offenders now living in Portland, and 27 of them would be barred from living near schools, parks and recreational areas under the police plan.

None of this, however, addresses the issue of whether distance requirements, in the absence of mandatory counseling or other remedial measures, are an effective tool.

Some believe that truly serious offenders should be given much longer sentences than the law allows at present, figuring that walls are better than rules for keeping children safe.

Lacking the societal will to do that, the current police proposal may provide the next best solution we have.