Pennock v. Dialogue

Pennock v. Dialogue

Pennock v. Dialogue

In the Pennock v. Dialogue case from 1829, Pennock (the plaintiff) was seeking a patent for improvements for making hoses he created but which were already being used by the public. The court ruled in favor of the defendant on the issue of patenting items already in the public's possession. The case was heard in the Circuit Court for the Eastern District of Pennsylvania.

Case Description

Pennock and Sellers created a new method for producing hoses to transport air, water and other fluids. They did not patent their new method when it was created in 1811. The public soon got hold of the new method for the improved art of making hoses and 13,000 feet of hose had been constructed in houses in Philadelphia. Samuel Jenkins claimed to have an agreement with the plaintiffs to sell and supply hoses to hose companies in Philadelphia.

Once the hose companies began producing hoses using the plaintiff's method the invention was in the possession of the public and were subject to public use. The plaintiff made no claim that from 1811 to the time they were ready to apply for an invention patent that they were improving their hose-making method. The plaintiffs did not claim to try and hide the new method of making hoses from the public.


The jury in this case ruled once an inventor willfully gives up their exclusive rights after an invention is created and a patent is not obtained, they cannot regain any rights once the public is in possession of those rights. An invention that is in the public domain cannot be taken out of that domain. Once an invention is legally open for public use it cannot be taken away because that would disrupt any growth or room for improvement within that invention. 

If the plaintiffs had successfully obtained an invention patent for their improvement to hose production they would have had a valid claim against those profiting off of their improved hose production method.

This case showed the importance of obtaining a patent. Inventing something and being recognized as the creator does not offer enough protection and rights to assure that the inventor will be the main person profiting off of their invention. If the public gets hold of the knowledge or a method for improvement before a patent is acquired, a patent request will be denied because the invention is a part of public domain.




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