Opinion No. (1991)

Richard C. Rice, Director Department of Public Safety Truman State Office Building Jefferson City, Missouri 65101

Dear Director Rice:

This opinion is in response to your question asking:

The installation and use of pen registers is authorized under Section 542.408(7), RSMo. The question of law is whether pen registers may be applied to crimes other than those involving "controlled substances," e.g., gambling, auto theft, prostitution and the like.

A pen register is a device which monitors what telephone numbers are dialed from a particular telephone, without intercepting the contents of any…