Article 87
(1) The patent applicant or the patentee shall not have a right to prevent the persons who used the invention domestically in good faith on or before the application date; or the persons against whom serious and real measures are taken for their use, from keeping using the invention subject to a patent in the same way or from beginning to use them in accordance with the measures taken. However, the subject persons keeping using the invention subject to a patent or using them in accordance with the measures taken can be allowed as much as to meet the reasonable needs of the business they own. The conferred right remaining from previous use cannot be expanded by issuing a license and this right can only be transferred together with the business.
(2) Practices regarding the products that are offered for sale by the persons mentioned in paragraph 1 shall be out of the scope of the rights provided by the patent.