In 1943 at the age of 21, Dave L. Cornfeld graduated from Washington University Law School, where he was a member of the Order of the Coif and editor of the Washington University Law Quarterly. For the next 71 years he practiced estate planning and tax law for Husch Blackwell LLC and its predecessors in St. Louis (except during his service in the United States Army).

He is a Life Member of the American Law Institute; Founding Member, Fellow and former Regent of the American College of Tax Counsel; and former Regent of the American College of Trusts and Estates Counsel. For the American Bar Association, he served as Vice-Chair of the Section of Taxation, for which he edited The Tax Lawyer; Chairman of the Committee on Taxation from Income from Estates and Trusts; and Senior Associate Editor of Probate and Real Property.

For over 20 years beginning in 1979, he taught and was a member of the Advisory Committee at the University of Miami's Heckerling Institute on Estate Planning, for which he published more than 20 articles. He also frequently spoke at numerous Estate Planning Councils, as well as the Southern Federal Tax Institute, the Mid-America Tax Institute (which he also chaired), the Tulane Federal Tax Institute, and many estate planning conferences such as those sponsored by ALI-ABA, the Illinois State Bar Association, and Indiana Bar Association, among countless other speaking engagements. For 21 years he was an adjunct member of the faculty in the graduate tax program of Washington University School of Law, where he taught "Fiduciary Income Tax" and "Taxation of Foreign Income and Aliens." He also co-authored Missouri Estate Planning, Will Drafting and Estate Administration (2 volumes, 1988) and its Supplement (2006).

In 2006, he was presented the Distinguished Law Alumni Award by Washington University School of Law. He has been selected by Best Lawyers in Trusts and Estates and in Tax Law every year since its founding in 1983 and was named "St. Louis Tax Lawyer of the Year" in 2012.

In the broader community, Mr. Cornfeld served for many years on the board of the Jewish Federation of St. Louis; the board of the Jewish Center for the Aged, where he was also legal counsel; and for 24 years on the board of United Hebrew Congregation, where he was also Treasurer, Vice-President, and legal counsel. He also served as general counsel of the St. Louis Community Foundation, a one hundred-year old philanthropic body that promotes local charitable giving.

He was married to Martha for 68 years before her death in 2011. He has three sons, eleven grandchildren and five great-grandchildren.