No US federal law explicitly prohibits players from using them, but they are not regulated by any US state authority. 
http://forum.fretky.cz/jak-ji-naucit-na-zachod-fretci-toaleta-a-vse-kolem/pengespill-pa-nettverk-t175642.html http://www.prepody.ru/topic37987.html http://forum.spolokmedikovke.sk/viewtopic.php?f=12&t=1134659 http://aficionado.pl/showthread.php?586541-Casino-P-Nett-Eigersund-eller-Casino-P-Nett-Alta&p=635209 http://forum3.bandingklub.cz/viewtopic.php?f=52&t=1578805 http://horsecity.ru/phpBB3/viewtopic.php?f=26&t=232648 http://forum.bandingklub.cz/viewtopic.php?f=28&t=1650833 https://talkingpoints.org/subx/showthread.php?tid=27083 https://wietmarkt.nl/viewtopic.php?t=346128 https://debate.socialism.nl/forum/showthread.php?tid=170381 https://debate.socialism.nl/forum/showthread.php?tid=201339 https://www.ww2.site/forum/viewtopic.php?t=78563 http://forum.terrassesdelancy.ch/viewtopic.php?t=158221 https://www.ww2.site/forum/viewtopic.php?t=296093 http://47.88.101.141/forum.php?mod=viewthread&tid=270483&extra= http://023002.com/forum.php?mod=viewthread&tid=1899245&extra= http://www.horsecity.ru/phpBB3/viewtopic.php?f=34&t=479151 http://www.prepody.ru/topic50319.html