Ziolkowski Patent Solutions Group, S.C. v. Great Lakes Dart Manufacturing, Inc.

¶ 1. Ziolkowski Patent Solutions Group (Ziolkowski), a Wisconsin intellectual property law firm, sued its former client, Great Lakes Dart Manufacturing, Inc., (GLD) for legal fees and 18% interest on the unpaid fees. Ziolkowski included a clause at the foot of its invoices imposing a finance charge of 1.5% per month on all accounts thirty days past due, but the original contractual engagement letter between Ziolkowski and GLD did not mention interest charges for late payments. The pertinent issue is whether a law firm is entitled to 18% interest on its unpaid legal bills when its attorney fee…