* What is staked must belong to the gambler and must be at his free disposal. It is wrong, therefore, for the lawyer to stake the money of his client, or for anyone to gamble with what is necessary for the maintenance of his wife and children.
* The gambler must act freely, without unjust compulsion.
* There must be no fraud in the transaction, although the usual ruses of the game may be allowed. It is unlawful, accordingly, to mark the cards, but it is permissible to conceal carefully from an opponent the number of trump cards one holds.
* Finally, there must be some sort of equality between the parties to make the contract equitable; it would be unfair for a combination of two expert whist players to take the money of a couple of mere novices at the game."