[dekhn]

Do you understand that the interpretation of unlawful purpose is left to the enforcement agency at the moment of possible infraction? Note that many municipalities in the US openly publish the names of people who are arrested, and what for, but then don't publish that people got off because they weren't guilty.

[ddlatham]

I totally agree that police at the moment would not likely respect the finer points of that law and may well detain you. I would not advise testing them. However, it's not likely that the DA would eventually be able to convict you. I was sharing what I found interesting about the actual law in question, which was a different impression than when I first read the claim that loitering at a school was illegal (which is technically true!) It's not actually illegal to watch kids play (with no other criminal purpose), even if we both agree that in practice you're likely to get a negative response.

[dekhn]

but you're basically just arguing that "intent matters", when it's clear (empircally) that it doesn't.

[ddlatham]

We agree that intent isn't likely to matter for what will happen to you that day. No one is arguing otherwise.

It does appear to matter in the law, and the day you show up in court (if you're foolish/stubborn enough to test it).