Edward Kleinbard, a prominent tax lawyer who helped global corporations find creative ways to cut their taxes before he moved to academia and shined a light on the practices of the types of companies he had once advised, died on June 28 in Los Angeles. He was 68.

He had been treated for cancer for several years, a brother-in-law, Kris Heinzelman, said in confirming the death, at Keck Hospital of USC.

Mr. Kleinbard’s career cut an unusual arc. He spent more than 30 years as a corporate tax lawyer, helping companies and financial institutions on Wall Street and elsewhere cut their tax bills. He then devoted the last decade to the cause of raising taxes, as a means of combating inequality and poverty. As a member of the law school faculty at the University of Southern California, he used his insider’s expertise to show in particular how multinational companies avoid taxes.

Mr. Kleinbard began to publish a series of articles on the inequities in the tax system, especially how multinational corporations like Google, using techniques nicknamed “Double Irish” and “Dutch Sandwich,” dodged billions of dollars in taxes by pushing profits into tax havens offshore.

He coined the term “Stateless Income” and titled an article on Starbucks’s tax avoidance “Through a Latte Darkly.”

In 2013, after a Senate investigation into Apple’s offshore tax strategy, Mr. Kleinbard summarized the company’s aggressive moves this way: “There is a technical term economists like to use for behavior like this. Unbelievable chutzpah.”

He became a regular contributor to The New York Times in its Op-ed online feature “Room for Debate,” and in 2014 he published his first book, “We are Better Than This,” which explored how tax policy could be used to solve the country’s surging inequality.

Most tax policy discussions were “backward,” he contended. Policymakers should identify their spending priorities — ideally to invest in the country’s citizens — and then discuss the proper tax policies to pay for them.

“The starting point in every case,” he wrote, “should not be determined by establishing an arbitrarily small amount of tax to collect, and then treating government like an institutional Procrustes, whose only responsibility it is to amputate the welfare of our fellow citizens to suit that amount.”

Michael Schler, tax counsel at the law firm of Cravath, Swaine & Moore, who had known Mr. Kleinbard since the 1970s, said of him in an interview: “He was one of the smartest tax lawyers around. Having been in private practice as a lawyer, he understood how big corporations are getting around and taking advantage of various tax rules. And by being in academia and by being a good writer, he was able to bring all that to the public’s attention.”

Mr. Kleinbard was known as a demanding boss and a perfectionist who required much of his colleagues — and of himself. He was sometimes described as a curmudgeon, but with a biting sense of humor, often delivered deadpan.

In one 2016 email exchange with this reporter, he asked for help in publicizing a Tedx Talk he had given on poverty and inequality.

“Kendall Jenner’s latest YouTube contribution has 4.5 million hits,” he wrote, “and I am trying to catch up.”

Edward David Kleinbard was born on Nov. 6, 1951, in Manhattan and grew up in Rye, N.Y. His father, Martin Kleinbard, was a litigator with Paul, Weiss, Rifkind, Wharton & Garrison. His mother, Joan Kleinbard, is an author who writes under the name Joan Gould.

Mr. Kleinbard graduated from Rye Country Day School in 1969 and earned both bachelor’s and master’s degrees in history from Brown University in 1973, writing his master’s thesis on Renaissance Venice.

He received his law degree from Yale University in 1976 and spent a year at Cravath before moving to the international firm Cleary Gottlieb Steen & Hamilton, where he practiced tax law for 30 years and became an expert on structuring complex tax-reducing financial instruments for Wall Street. He was an adviser to some of the country’s biggest investment banks, including Goldman Sachs and Citigroup.

In 2007, in an unusual move for a senior corporate lawyer, he left Cleary Gottlieb and became the chief of staff for the Joint Committee on Taxation, a nonpartisan joint congressional committee that helps lawmakers on prospective tax policies.

But he grew frustrated with the slow pace of the legislative process and left the committee in 2009 to join the law school faculty at U.S.C., where he taught tax law. He also pursued his love for photography, hiking and long-distance bicycling, which took him across the United States, Canada and Europe.

In addition to his mother, Mr. Kleinbard is survived by his wife, Norma Cirincione, with whom he no longer lived; his son, Martin; his sister, Kathy Heinzelman; his brother, David; his partner, Suzanne Greenberg; and a granddaughter.

Mr. Kleinbard submitted to his publisher the manuscript for a book the day before he went into the hospital for surgery in March, said Leslie Samuels, a senior counsel at Cleary Gottlieb who had worked with Mr. Kleinbard there. The book, titled “What’s Luck Got to Do With It?,” explores the role luck plays — whether through inherited wealth, geography or racial heritage — in worsening inequality.

Mr. Samuels recalled how Mr. Kleinbard would roll his eyes at how many of his wealthy clients were oblivious to their good fortune. He recalled Mr. Kleinbard saying: “They’re not so smart — they are just lucky. I was lucky.”