Ross thought that all people should be benevolent and so if lying affects one's benevolence, one needs to decide if lying is better for the sake of benevolence.
Ross' non-absolutist take to ethics is preferred because is considers what is morally right in certain situations. In the instance of a Poker game, it is a game that relies upon lying or "bluffing" so it actually does pass Kant's universal law test. Kant would probably not take issue with the game of Poker because it is a game that needs the aspect of bluffing in order to work. But, if we want to use the example and examine it purely from a Kantian perspective on lying, then we must consider that people are acting from a means approach and not an end approach and all of the players have the same intention in mind -- to wind the game -- and thus they have to use lying as a means to get what they want (the pot of money).
W.D. Ross's prima facie duties are always more "moral" than Kant's absolutist duties. For example, the duty to help other people must always be considered, however we also, according to Ross, have the duty to always keep our promises. So if we have promised to take our friend to the airport but on the way to the airport we witness a very serious accident, we have the moral duty to stop and help others. We can weigh stopping against breaking...
We may decide to stop and help and call our friend and say she will have to take a cab. The friend will more than likely understand because of the fact that there are lives that are hanging in the air. However, if we just decide that we are too tired to drive to the airport to get our friend and so we call and lie, this would be wrong in Ross's opinion because we are, first of all, not acting in a benevolent manner as well not keeping a promise. Weighing the prima facie duties against one another makes more sense than saying that we can never lie or we can never steal. What if we had to steal a loaf of bread or our children would die from starvation? Ross would have us weigh the prima facie duties against one another in this case and though we have the duty to not harm others, we also have the duty to help others. If stealing the bread was from a wealthy storeowner, then we may believe that what we are doing is right because we are feeding our children. Kant would say that stealing is never right -- no matter what. Non-absolutism is a better system for acting morally.
References
Bennett, Jonathan. (2010). Groundwork for the metaphysic model. Immanuel Kant.
Ross, W.D. (1930). What makes right acts right? The right and the good. Oxford: Oxford
