legal ground
Article 61 of the Patent Law of People's Republic of China (PRC)
Where a patent infringement dispute involves a new product manufacturing method invention patent, the unit or individual that manufactures the same product shall provide proof that its product manufacturing method is different from the patented method.
Article 69
In any of the following circumstances, it shall not be regarded as infringement of the patent right:
(1) The patentee or a unit or individual licensed by the patentee uses, promises to sell, sells or imports its patented products or products directly obtained by patented methods;
(2) Having manufactured the same product, used the same method or made necessary preparations for its manufacture and use before the patent application date, and continuing to manufacture and use it only within the original scope;
(5) manufacturing, using or importing patented drugs or patented medical devices for the purpose of providing information required for administrative examination and approval, or manufacturing or importing patented drugs or patented medical devices exclusively for them.