The Justice Department filed a civil suit claiming Grinnell Corporation had a monopoly in the operation of central station hazard-detecting devices. These security devices are used to prevent burglary and to detect fires.
They involve electronic notification of the police and fire departments at a central location.
Grinnell, through three separate subsidiaries, controlled 87% of that business. It argues that it faces competition from other modes of protection from burglary, and therefore it does not have monopoly power. What argument does the Justice Department have to make to prove its claim that Grinnell is operating an illegal monopoly?