 Behavioral economic analysis of law takes three forms. The first accepts the formal framework of rational choice but rejects the interpretation of preferences in this framework as self-interested. Call this the “broad RCT” branch of behavioral economics. The other two forms of behavioral economics derive from psychology which seeks to understand the mental processes that agents actually deploy in their decision making. Both of these forms of behavioral economics reject the apparent assumption of the classical model that agents consciously and directly maximize their preferences. But each form adopts a different stance towards human rationality. The “fast and frugal heuristics” branch claims that agents are ecologically rational. The heuristics and biases form of behavioral economics contends that agents are not rational. We discuss these in turn. 