Adoption of an Open Occupancy Statute; (f) member of the Mayor's Citizens Committee on City Revenue and Expenditures (1963); and (g) from December 1961 to April 1970, Leighton was a member of the Public Review Board, UAW.
Presently he is (1) member of the Board of Directors, Grant Hospital, Chicago, Illinois; (2) National Member of the Harvard Law School Association; (3) member of the Board of Directors of the Chicago Tuberculosis Institute; (4) member of the Chicago Committee on Urban Opportunity.
In 1951, together with the late Loring B. Moore, Leighton organized the law firm, Moore, Ming & Leighton, predecessor to the law firms of McCoy, Ming & Leighton (1959-1964) and McCoy, Ming and Black, 123 West Madison Street. Among the partners in the firm were Fleetwood M. McCoy, William R. Ming, Jr., Walter K. Black and Chauncey Eskridge. From 1953 until 1971, the law office occupied the third floor of the Joel Hunter Building, Chicago, Illinois, and was considered by the profession to be one of the largest predominantly Black law firms in the United States. Leighton withdrew from the firm in November 1964 when he was elected a judge of the Circuit Court of Cook County.
During his law practice, Leighton was active in cases that attracted national attention. The first and perhaps the most important of these was the Boswell Amendment Case in which as counsel for ten Negro citizens of Mobile, Alabama, he succeeded in obtaining a judgment declaring the amendment unconstitutional. The opinion of the three judge federal court is reported in Dams v. Schnell, 51 F. Supp. 872, and was affirmed by the Supreme Court of the United States, sub nom. Schnell v. Davis, 336 U.S. 933, 69 S. Ct. 749.
In 1950, Leighton represented Negro parents of school children in Harrisburg, Illinois in a proceeding which he filed in the United States District Court for the Southern District of Illinois. An injunction was obtained ordering desegregation of the public schools of Harrisburg, Illinois.
In the years before 1964, Leighton's important cases involved convictions of men whose constitutional rights were infringed in the trial court proceedings. The most famous of these was that of Earl Howard Pugh who spent seventeen years of penitentiary imprisonment before he was discharged in a proceeding instituted in the Criminal Court of Cook County. In 1953, the Illinois General Assembly passed a bill which authorized the payment of $51,000.00 to Pugh. The story of the case was published in Ebony Magazine, October, 1955. Other cases of constitutional importance were Napue v. Illinois, 358 U.S. 919; Ciucci v. Illinois, 353 U.S. 982; Townsend v. Sam, 372 U.S. 293, See 334 F.2d 838; Goldsby v. Harpole, 263 F.2d 71; Lloyd Eldon Miller, Jr. v. Pate, 226 F. Supp. 541; See 87 S. Ct. 785.
During his professional career, Leighton represented plaintiffs and defendants in civil cases of every kind. He defended more than 200 criminal charges in bench and jury trials. During this same period he handled more than 175 appeals or reviews, civil and criminal, in state and federal courts.
In addition to these cases, Leighton attracted professional attention of the Bench and Bar in his handling of the habeas corpus proceedings of Lloyd Eldon Miller, Jr. v. Pate, a case in which a death sentence imposed in Hancock County, Illinois in 1956 was set aside by the United States District Court for the Northern District of Illinois. Lloyd Miller was released from incarceration after the decision of the United States Supreme Court reported in 87 S. Ct. 785.
In July, 1963, Leighton attracted nationwide attention when he represented a well known alleged underworld figure in Sam Giancana v. Marlin W. Johnson, United States District Court, Northern District of Illinois. This case resulted in a rarely granted injunction restraining the Federal Bureau of Investigation from alleged invasions of the plaintiff's civil liberties. One unexpected consequence was the imposition of a fine on an Agent-in-Charge of the Federal Bureau of Investigation, a fine later upheld in the United States Court of Appeals and reported in Giancana v. Johnson, 335 F.2d 372 (7th Cir. 1964).

During his years at the Bar, Leighton has been a member of the American Bar Association, the Inter-American Bar Association, the National Bar Association, the Massachusetts Bar Association, the Illinois State Bar Association, the Cook County Bar Association, the National Association of Defense Lawyers in Criminal Cases, and the Chicago Bar Association.
He is a member of several committees of the American Bar Association: Rights and Responsibilities, Judicial Administration, Legal Education. In 1963-64, Leighton served as the Chairman of the Bill of Rights Committee of the Illinois State Bar Association.
He served on committees of the Cook County Bar Association. He has been active in the National Bar Association and has been a member of several of its panels at its national conventions in various parts of the United States.
In the Chicago Bar Association, Leighton was the first member of his race to be elected to its Board of Managers. After serving two years, he was honored with election as Librarian, a position to which he was reelected for two consecutive terms following his original term in that office.
Until November 1963, Leighton served as a Commissioner of the Supreme Court of