The purpose of this chapter is to introduce a new research field within experimental jurisprudence—which we refer to as experimental longtermist jurisprudence—aimed at informing legal-philosophical, doctrinal, and policy debates relating to the long-term future, and in particular the interests of future generations. Historically, the interests of future generations have been neglected by legal systems, which fail to grant them democratic representation in the legislature, standing to bring forth a lawsuit in the judiciary, and serious consideration in cost-benefit analyses in the executive. Recently, this neglect has increasingly been called into question based on normative philosophical arguments relating to the value of future generations; empirical evidence relating to the severity of the risks faced by future generations relative to those faced by previous generations; and legal reforms attempting to codify the interests of future generations via constitutional provisions. Experimental longtermist jurisprudence uses methods from experimental psychology to help identify the source of this disconnect, and in turn to help determine the appropriate level and form of legal protection for future generations. In this chapter we (a) provide an overview of the substantive and methodological underpinnings of experimental longtermist jurisprudence; (b) introduce three research programs within experimental longtermist jurisprudence; and (c) discuss the normative implications of each of these three research programs.