Johnston is co-owner of Sidetrack bar in Chicago, and a long-time activist on GLBT and AIDS issues.

His involvement as a volunteer includes the Tavern Guild in the 1970s, Chicago Metropolitan Sports Association ( formerly Gay Athletic Alliance ) , and Gay and Lesbian Town Meeting. He served on the boards of GAA/CMSA, the North American Gay Amateur Athletic Alliance, Harvey Milk Fund, the Northalsted Area Merchants Association, IMPACT, and the Illinois Federation for Equal Rights ( now Equality Illinois ) . He and partner Pepe Pena have donated to dozens of GLBT and AIDS causes. Johnston is also a founder of CAMMP, Coalition Against Media/Marketing Prejudice ad Equality Illinois.