I couldn't even say for the U.S., let alone Sweden. Here in the U.S. it depends on the state, the law enforcement agency, the specific officer... Maybe a few minutes, maybe days, maybe weeks? I have a friend arrested for breaking into people's cars, granted he was guilty (but also underage at the time), they used his shoes to identify him by shoeprint. He admitted it, paid restitution, paid fines, went to alcohol counseling, did community service... but it took him a year to get his shoes back from the police station. So if they confiscate your
ecig, test it, let you go, find nothing illegal, don't expect to get your equipment back anytime soon, if ever.
I also had a friend get a ticket for drug paraphernalia for a roach clip. There wasn't even any illegal residue on it to test, and owning one itself isn't illegal, but it didn't stop them from writing the ticket, and he didn't know enough about his rights to contest it.
Never trust a cop. I've had them freak out on me for a number of totally innocent items in my car after being pulled over for stupid stuff like a plate light that is too dim or whatever. They've hassled me for having an air compressor in my back seat, for having speaker wires in my car with no speakers attached, for having pages torn out of a phone book on my dash. They've searched my car and even gone through the trash on the floor of my car only to find nothing, and then be ...... about finding nothing.
I've been hassled so much by cops, I wouldn't give using my
ecig in public a second thought. If they hassle me for it, they hassle me, in the end the can suck my ....
But that's just me, and that's just here in the U.S.
