Before being appointed to the Superior Court, Judge Cahill was a construction lawyer at the law firm Bronson, Bronson & McKinnon. He represented design professionals, owners, contractors and subcontractors, both in litigation and as corporate counsel. His practice included representing the design engineer in a dispute of the design outfall in Bombay, India, representing the owners of Fillmore Center during construction of a high rise project in San Francisco, and representing various parties in smaller infrastructure and construction cases. In addition, he served as corporate counsel to a major engineering firm as well as smaller subcontractors.
During the time he served on the court, San Francisco constructed a $50 million courthouse and Judge Cahill represented the court, as owner (the Superior Court of San Francisco), in interacting with contractors, architects, and public entities as well as other judges and city officials. He was deeply involved in the project for seven years, from the initial planning, financing, design, and construction through the mediation in which the contractors' claims were resolved and the courthouse opened.
- Arbitrated infrastructure dispute regarding design and construction of a "stadium seating" movie theatre in a major public mall in California
- Matter involving disputes between the owner and the design professionals regarding the earthquake retrofit of the Golden Gate Bridge in San Francisco
- Mediation involving reconstruction of a gas fired power plant in California after a fire destroyed much of the plant
- Mediation involving several-million-dollar dispute between owner of a power plant in Florida and design engineer for the project
- Member of a Design Review Board which reviews disputes that occur during renovation of a Hospital in the Bay Area
- Sole arbitrator/judge in an infrastructure dispute regarding construction of a commuter train system in the Bay Area