In the case of Rumford Chemical Works v. Hygienic Chemical Company of New Jersey, 1909, the U.S Supreme Court was tasked with determining whether a patent held by Rumford for an improved baking powder formula had been infringed upon by Hygienic. The key issue at hand was whether or not the use of acid phosphate in place of cream tartar constituted infringement on Rumford's patent. The court ruled that it did not constitute infringement as they were different substances and thus produced a different product altogether. This ruling established that minor alterations to patented formulas which result in substantially different products do not infringe upon existing patents.

In the dissenting opinion for Rumford Chemical Works v. Hygienic Chemical Company of New Jersey, it was argued that the majority's decision to uphold a patent infringement claim was incorrect. The dissenting justices believed that there were significant differences between the patented process and the one used by Hygienic Chemical Company, which should have been enough to dismiss any claims of infringement. They also disagreed with how much weight was given to expert testimony in this case, arguing that such testimonies can often be biased or unreliable due to conflicts of interest or lack of understanding about complex technical matters. Furthermore, they felt that upholding this claim could potentially stifle innovation and competition within the industry as companies may become hesitant to develop new processes out of fear they might inadvertently infringe on existing patents.