PayPal is an international person-to-person (P2P) instant-pay service, but it cannot be used to fund your account at overseas online casinos because of various banking regulations. In America, the regulation in question is the UIGEA, which is a mechanism by which online gambling transactions to or from non-US-licensed casinos and gambling sites are blocked automatically. This is the same reason why credit card deposits are sometimes declined when trying to top off your online casino bankroll. Of course, these kinds of restrictions are targeted at banks, not individual players, and you are breaking no laws when using PayPal for online betting through the private voucher/transfer method or via MatchPay.