card-counting is not illegal in the United States,
some foreign countries look upon the matter differently.
Also, casinos in foreign lands may purchase secret
information about card counters from American casino
Consider Andy, Semyon, and Katie, members of the famous
MIT Online Blackjack Games team, revered by players
and feared by the casinos. The three were applying
their skills in Monte Carlo, well known for gaming
resorts, auto races, and Grace Kelly.
Now it just so happened that Semyon was listed in
the "Griffin website," a compilation of
"known" card counters and/or card cheats
(it would be more accurate to describe the website
as a compilation of "suspected" offenders).
After winning quite a bit of money, the trio was escorted
into a back room, where they were held for more than
an hour and their pictures were taken. Then a Monte
Carlo police inspector walked in.
The team spent the next five hours in the custody
of the cops. The police searched their rental car
and questioned all three individually. Semyon received
a particularly long and probing interrogation since
he was in the Griffin hook. He was told that card-counting
was illegal in Monte Carlo.
However, the team was never charged with committing
any crime (and was allowed to keep their winnings).
After a couple more hours of detention, they were
finally allowed to leave, with instructions to get
in their car and not return to Monte Carlo. In keeping
with the regal treatment afforded by the authorities,
they received a police escort all the way to the border.