David C. Baldus was born in Wheeling, West Virginia in 1935 to Frank A. and Mary Baldus. He studied Government as an undergraduate at Dartmouth College, graduating in 1957, before serving with the Army Security Agency as a Lieutenant in Korea from 1958 to 1959. Baldus attended graduate school at the University of Pittsburgh where he was active in a number of political groups such as the Young Democrats and the Americans for Democratic Action. He obtained a Master of Arts in Political Science in 1962 and went on to study law at Yale University earning the LL.B. degree in 1964 (equivalent to a J.D.). He returned to practice law in Pittsburgh before obtaining his LL.M. degree from Yale in 1969. During this time Baldus was elected as the Democratic County Committeeman for the 4th District, 7th Ward in Pittsburgh in 1966, and also served on the Pennsylvania Constitutional Convention from 1967-1968. In 1969 he was appointed to the faculty at the University of Iowa College of Law, an affiliation that would last over 40 years. He was appointed full professor in 1972 and the Joseph B. Tye Professor of Law in 1983. Baldus also directed the Law and Social Sciences Program at the National Science Foundation from 1975-1976, and was the director of the Center for Interdisciplinary Legal Studies at the Syracuse University College of Law from 1981-1982.

Baldus taught at the University of Iowa College of Law for over 40 years, instructing students in Iowa Criminal Law, Federal Criminal Law, Admiralty Law, and Capital Punishment, as well as a theory course on abnormal criminal cases. He served a prominent role on the Faculty by participating in promotion and term reviews for professors both at Iowa and in the field of Criminal Law. Baldus also chaired the Academic Standards and Review Committee in the mid-2000s, which dealt with evaluations and issues of plagiarism.

In the early 1980s, Baldus began a study of the implementation of the death penalty in Georgia. The Georgia capital sentencing system had been declared arbitrary and unconstitutional by the Supreme Court in theFurman v. Georgia (1972) decision, causing ade facto nationwide moratorium on the death penalty. In the aftermath of the decision, Georgia and other states began implementing new sentencing measures in an attempt to impart objectivity and standardization. This included measures such as separate penalty trials, the codification of aggravating and mitigating factors, and the separation of murder into different degrees of severity. Four years afterFurman, the Supreme Court upheld the new practices in three out of five states in a set of decisions headed byGregg v. Georgia (1976) effectively defining a path where states could again legally sentence defendants to death. This new system was first challenged inMaxwell v. Bishop (1968) where a study performed by Marvin Wolfgang and Marc Riedel argued that the capital sentencing process was discriminatory towards African American defendants. During Maxwells appeal, future Supreme Court Justice Harry Blackmun rejected the Wolfgang study because it did not specifically examine the county where Maxwell was convicted, and because only controlled for 29 other variables, apart from race.

Decided in 1987, the Supreme Courts ruling inMcCleskey v. Kemp became the most prominent challenge to capital punishment in the port-1976 era, and perhaps the most significant modern ruling on racial discrimination in the justice system. In a 5-4 split decision, the court ruled that, while Baldus's evidence showed significant racial discrimination in the capital punishment charging and sentencing system as a whole, the appeal failed to prove discrimination in the specific case of Warren McCleskey. The decision essentially barred the use of statistical evidence to prove unconstitutional discrimination in the justice system. Warren McCleskey was executed using the electric chair in 1991. After his retirement justice Lewis Powell, who authored the majority opinion, stated that theMcCleskey ruling was the decision he most regretted.

After his prominent work on the Georgia capital system, Baldus's research turned to focus on discrepancies in Tort law, a field he would publish in during both the late-1980s and mid-1990s. Making use of this experience with social science research, he sought to develop the methodology and procedures used to conduct an empirical study on the review of awards made by juries in state courts for noneconomic damages. Notably, this came in the form of damages for medical malpractice. Baldus found these awards to be inconsistent and perhaps excessive. To establish more predicable awards, he developed systematic classification systems for Additur and Remittitur review of damages.

Baldus had gained substantial notoriety for is work inMcCleskey. In the 1980s, the New Jersey Supreme Court requested a proportionality review of its capital sentencing system and appointed Baldus as Special Master to conduct the study. The case in question was the appeal of Robert O. Marshall who was convicted of hiring someone to kill his wife in 1984. Although the New Jersey court recognized statistical evidence of discrimination would pose a structural challenge to the state capital system, the New Jersey Proportionality Review failed to show evidence as strong as that which was presented inMcCleskey. Baldus was not able to use logical regression because the regressions did not converge. Instead he relied on discriminate analysis, which, while finding significant race-of defendant effects, was more susceptible to methodological criticism. As a result,State v. Marshall was the first post-Furman capital appeal that was upheld by the New Jersey Supreme Court. The state later performed two more proportionality reviews performed by different Special Masters before becoming the first state to abolish the death penalty by legislation in 2007. Robert O. Marshalls sentence was reduced to live in prison in 2006. He spent a total of 30 years in prison before dying in 2015 at the age of 75.