Section 68

In any proceedings for the infringement of a patent, where the subject matter of the patent is a process for obtaining a new product, the burden of proving that a product is not made by the process is on the alleged infringer if the product is new or a substantial likelihood exists that the product is made by the process and the proprietor of the patent has been unable through reasonable efforts to determine the process actually used.

In considering whether a party has discharged the burden imposed upon the party by this section, the court is not to require the party to disclose any manufacturing or commercial secret if it appears to the court that it would be unreasonable to do so.