A cottage industry has developed around the so-called “rocket docket” of the Western District of Wisconsin, the speed of which has attracted plaintiffs in patent cases.

Public transit agencies nationwide are being targeted with questionable lawsuits by so-called patent trolls squeezing settlements out of financially strapped public entities unable to mount legal defenses against claims they are infringing on intellectual property protections, industry representatives said Thursday.

Plaintiffs Rockwell Automation Inc., a Wisconsin corporation, and Rockwell Automation Technologies Inc., an Ohio corporation, filed a lawsuit Nov. 16, 2010, in federal court against defendants Germantown-based WAGO Corp. and its German parent company, WAGO Kontakttechnik GmbH & Co. KG.

DuPont officials plan to appeal a federal jury’s record-setting $1-billion verdict that found the company willfully infringed a patent held by Monsanto.

A new study purporting to answer the question of where attorneys should file patent cases gives high marks in opposing areas to both Wisconsin districts.