In Alley v. MTD Products, (WD.Pa. 2018, Case No. 3:17-cv-3), Judge Kim Gibson of the U.S. District Court for the Western District of Pennsylvania highlighted and discussed two often overlooked and under-appreciated aspects of discovery: the extent that one can undergo an inquiry that involves “discovery on discovery”; and proportionality as a limit on discovery.

Alley is a products liability action brought by a plaintiff against the manufacturer of an allegedly defective snow blower. In his complaint, the plaintiff alleged that he was injured when the “plastic rim” of the snow blower’s tire burst during an attempt to inflate the tire using an air compressor.