Lindberg was the vice president and legal counsel for John E. Reid and Associates in Chicago from 1955 to 1968, becoming an expert in financial fraud investigations.

[3] During his tenure in the General Assembly, Lindberg was a private practice attorney in the Chicago suburb of Crystal Lake in McHenry County from 1968 until 1973.

[2] His proposed legislation provided for campaign disclosures, but these provisions did not make the final bill passed by the General Assembly.

[3] Lindberg's voluntary disclosure of personal political spending from his 1972 campaign—something he did every year as comptroller—was a first for an Illinois statewide-officeholder, and drew widespread praise.

After completing his term as comptroller, Lindberg was appointed Deputy State Attorney General for the state of Illinois, and served from 1977 to 1978 before winning election in 1978 as a judge in the Illinois Appellate Court representing the Second Judicial (Elgin) District.