Insulet (NSDQ:PODD) is suing Roche Diabetes Care in the U.K., claiming that Roche prematurely began selling tubeless insulin pumps covered by an Insulet patent three years before that patent expires.

The trial for the lawsuit, filed in August 2020, began this week in the U.K. High Court.

Insulet claims that Roche has been infringing the patent on its Omnipod insulin pump by marketing Roche’s Accu-Chek Solo pump since mid-2018. Accu-Chek received the CE mark in July of that year. Insulet also claims that Roche is indirectly infringing its patent by marketing  “consumable” products needed to operate its Accu-Chek pumps in the U.K.

Insulet has asked the court for an injunction to stop Roche from marketing these products until Insulet’s patent expires on Aug. 31, 2021. It is also asking for unspecified damages dating from the time Roche began marketing Accu-Chek and its consumables in the U.K.

Roche declined to comment.