The telephone company, at police request, installed at its central offices a pen register to record the numbers dialed from the telephone at petitioner's home. Prior to his robbery trial, petitioner moved to suppress "all fruits derived from" the pen register. The Maryland trial court denied this motion, holding that the warrantless installation of the pen register did not violate the Fourth Amendment. Petitioner was convicted, and the Maryland Court of Appeals affirmed.
Harry Andrew Blackmun
William Joseph Brennan
Howard L. Cardin argued the cause for petitioner. With him on the brief was James J. Gitomer. Stephen H. Sachs, Attorney General of Maryland, argued the cause for respondent. With him on the brief were George A. Nilson, Deputy Attorney General, and Deborah K. Handel and Stephen B. Caplis, Assistant Attorneys General.