Should We Have to Have Our ID card checked everytime we walk into a public library?

That's a proposal that making the rounds and apparently gaining momentum in several Massachusetts towns The ostensible purpose, keeping libraries safe from rapists and child molesters by having names and photos of library patrons checked against a database of registered sex offenders, seems on its face well-meaning and innocuous enough, as encroachments against basic freedoms often do. Of course, even if you accept the (dubious) premise that showing ID will deter sexual criminals, what's the use of checking names of only local registered offenders when a rapist could come from elsewhere in the county or state. Why not check names against wider available databases. And, while we're at it, why not (in the name of safety, of course) check ID against other databases to screen for other kinds of potential criminality. Or to make sure illegal immigrants aren't reading books at taxpayer expense.

Is it really just paranoia to see the introduction of library checkpoints as another step toward having ID checks routinized in other areas of public space (malls, parks, you name it).