Exact same story happened to me 2-3 months ago in europe.
I resume:
I was parked in a shopping center sending email on a free wifi.
I was parked close of a shop entrance door, laptop open , sending email for 30-40 minutes...
2 cops in civil came show their badge, grab my laptop, place it on the car, took a picture of my screen.on the screen was printed "xxx(name of the shop)"on the connection page .Bingo, I was caught!!!

then they asked me to come in their car, went to police office. asked me questions for 40 minutes.I explained them how wifi worked.
the cop said: "ha i see, it is like in the airports..."
After they looked at my files (the other cops was on my laptop all the time)in my computer, I signed a deposition.
1 month later, 500$ fine, plus criminal charge for 1 year and a promess I will not do it again (from the procuror)."oops baby I did it again"
ah ah ah!
I sent a full opposition with an explaination sent by post letter, I wrote things like that: " broadcasting, internet sharing, unprotected wifi, responsability of the broadcaster, no law in my country"etc etc
now, here 2 possibilities:
1. the guy give up!(the shop owner where I was parked a few feet in front of his entrance door)
2. the guy is really mad at me, and go further. It means judge, attorney,paperwork, money, long waiting time...
for my part I am ready to see the judge(I will not have the choice if i dont want be fined for a non show up anyway) ,I will not pay for an attorney or ask for a free attorney. I can defend myself.I hope it stops here!
Personally I think the guy will give up. Apparently he doesnt know anything about computer and jsutice here can take months, years,....they have thousand of criminal to prosecute, people waiting in jail, illegal immigrant to kick out,...do you think they care of a simple guy like me sending some emails to friends?
many people think they just have to buy a router with a wifi or a wifibox sold when they signed up for ADSL, and they do not realize that their equipment is broadcasting publicly all around with a coverage of 300-500 radius.they are unaware of this small antenna on their system or unaware its broadacsting beyond their shop , home, or garden.Like if radiowaves know exactly where to stop!
or they are clueless how to install and to configure properly their system (no encryption key , no passcode,...)
People doing that are stupid or they want share their internet connection with other(like me).
I have installed same system at my dad' home, and it is public for everybody who want parc near the house. what would happen if my father start to sue the poor guy connected on his ADSL?
If I am guilty of"stealing internet" and I become a criminal, I could sue the department of telecom in my country. I could sue the shop who sold me the laptop, I could sue intel, microsoft. Com'on, call your technician and install properly your system if you can not do it yourself!.
I even found a portable wifi detector.it costs 30$.
BTW ,during 3 months, I was connected on the cops' adsl....from a cafeteria just close of the main police office.("oops I did it again baby")
if i have agreed to pay the fine sent by the procuror , it means I am making a crime 3-4 times a week because I continue to send emails from cafetria,parking slot,... and I dont want to have a criminal file unless I am (properly)found guilty.
the law in my country says something like that:"it is illegal to fraud a paid public service , by mean of computer, ..."it doesnt say more.nothing about ADSL, wifi,...
have fun with that!
(sorry for by broken english, not my first language)