In my first article, I discussed the consequences of a public disclosure of your invention prior to filing a patent application.  In this article, I want to discuss the U.S. on-sale bar.  It's another way in which you may inadvertently lose rights due to your own actions prior to filing a patent application. 

This bar is created by U.S. legislation which requires that a U.S. patent application must be filed within one year after an offer for sale in the United States of a product which includes the invention.  The on-sale bar applies regardless of whether the offer for sale was a public disclosure or not. 

It's a trap for the unwary because it's often forgotten.  For example, if you meet with your U.S. customer at his U.S. premises to show the customer a prototype of a new product (to determine whether the customer would be interested in purchasing the product), then that would probably be an offer for sale, and it was made in the U.S.  In this hypothetical scenario, if you do not file a patent application in the U.S. within one year after your meeting with the customer, you probably are unable to do so thereafter.  

Whether any particular discussion with a customer is an offer for sale establishing the on-sale bar depends on the facts.  For example, U.S. case law has established that, for the on-sale bar to apply, the invention must be ready for patenting (i.e., at least sufficiently well described to enable one skilled in the art to make the invention) when the offer for sale is made.  Also, to establish the on-sale bar, the offer for sale is required to be made in the United States.  So, in any particular situation, it may not be clear that the on-sale bar applies. 

The on-sale bar applies only in the United States.  It can prevent you from obtaining patent protection in the U.S. only. 

To summarize:  In any situation where you are about to discuss your new product with a U.S. customer, you should consider whether the discussion will create an on-sale bar.  If it does, then you need to file a U.S. patent application within one year of the discussion.  If you're in doubt, then filing a patent application promptly after the discussion would be prudent.  Of course, filing a patent application before any discussion of a new product with a U.S. customer would be even better.