If you are wondering why the latest sex offender bill passed the Iowa Senate 49-0 last night, here’s a guess: it is dangerous to be on the losing side of anything related to sex offenders.

There are few images more effective in a campaign mailer than a photo of a sketchy guy’s shadow superimposed on a sidewalk next to a playground.  Or a photo of kids looking vulnerable, without their parents in sight, with apocalyptic text asking “Why does candidate X refuse to protect our children?”

The most recent, high-profile example of this tactic came from an independent expenditure during last year’s Democratic primary for the 3rd Congressional District.  Former State Rep. Ed Fallon, famous for being a lone “no” vote on countless bills during his time in the legislature, was attacked in mailings because he voted against Iowa’s original “2,000-foot rule,” which prohibited sex offenders from living near schools and certain other places where children congregate.

“Ed Fallon thought it was more important to cast his vote to make a political statement than to cast a vote that protects our kids from these dangerous predators,” the mailing said, beneath a photo of an inmate watching children at play.

Ironically, nowadays almost everyone — lawmakers, analysts, and peace officers — agree that the old law was inadequate and potentially counterproductive.

In the Senate, the issue was pretty cut-and-dried, and both the Democratic and Republican caucuses supported the new bill.  The House appears to be more fractured (as has often been the case this year), with GOP leaders saying they plan to try to kill significantly alter the measure.

That is probably making a lot of state representatives from both parties nervous.  During the next campaign, both sides of the issue could cast the other as soft on sex offenders.  A “yes” vote would allow more sex offenders to live near schools, but it would also allow law enforcement to arrest the most serious offenders for loitering near a school, even if they don’t live there.  A “no” vote would allow sex offenders to continue loitering near children without much interference from law enforcement, but it would keep the stricter 2,000-foot rule in place.

In the strained logic of a direct mail campaign, either vote could have dire political consequences, and the winning side will be the one that is willing to make the most intellectually dishonest argument.  That’s not a good place for the state of Iowa to be.

On sex offender bills, legislators must seek strength in numbers if they hope to avoid a messy and expensive direct mail war in 2010.  Only an overwhelming vote in one direction or the other can prevent it.