Detroit Water and Sewage Department not responsible for negligence in causing gas leak and explosion

In Butler, et al.  v. Michigan Consolidated and Detroit Water and Sewer, the plaintiffs attempted to hold the City responsible for the destruction of their businesses, after it ruptured a gas distribution line, causing an explosion and fire.  The Court held that it did not matter if the City crew was negligent because the City enjoyed immunity from liability for its own mistakes.