Actually every country has it's law especially when it comes to gambling business in which every country has it's law about the legalization of their business so that it would not be illegal after all, it is a important matter that the gambling business is licensed altrady so that the clients also will not be afraid to play on your bitcoin casino, better if you will be able to look some lawyer or attorney on what you need to do in order to start a bitcoin casino that is legal because in my country you need to have a business permit before you operate any business especially with gambling business or casinos.