In this talk, I will survey a few recent projects that exploited changes in the law (for example, the enactment of a statute or the issuance of a Supreme Court decision) to examine whether law influences attitudes and behaviors - and how. The talk will discuss key methodological issues, including the multitude of options to measure law's effects, how to find opportunities to conduct field experiments and longitudinal studies, obstacles and limitations. Examples and evidence come from Israel and the United States, including the enactment of Israeli Nation Law and the landmark Masterpiece and Fulton United States Supreme Court decisions