As you may know, one of the most common ways to make money off of patents is to sell it. When there is a change of ownership of a patent or a patent application, you need to document it (as you would with many legal procedures). This is called an assignment, and it is an important document that must be recorded at the USPTO in order for the assignee to have a proper ownership of the assigned patent.
Under the rules, you have three months to record an assignment. Otherwise, a subsequent bona fide purchaser (someone without notice of the assignment) can subordinate the original assignee's rights. How do you record an assignment? First, you need to have an assignment agreement.
Here are the things that you need to have a legit assignment agreement.
First, you need to clearly express in writing that there is a transfer of the intellectual property in question. You can do this by identifying patent application serial numbers, patent numbers, titles, attorney docket numbers, etc. Then you need to identify the proper parties, i.e., assignee(s) and assignor.
The assignment document must be signed by the assignor, and in some cases (e.g., foreign assignments), also by the assignee. And while not required, I would highly recommend you to have the assignment document notarized or signed by witnesses.
When should you execute and record a new assignment document? The short answer is: when there is a change in party and/or change in the patent or the patent application. Another way to say this is: when in doubt, execute a new assignment document. Basically, the goal is to make sure that there is a clear chain of ownership and to eliminate any confusion as to what the assigned patent or patent application is.
For example, let's say you've assigned your patent to your friend. A few years go by and your friend decides that he doesn't want the patent anymore, so he gives it to his sister. When the friend gives the patent to his sister, the friend must execute a new assignment agreement. What happens if your friend changes his name? Then the parties remain the same but I would still recommend filing a new assignment agreement to avoid any confusion.
In another example, you assign your patent to Company A and it turns out you were supposed to assign the patent to Company B. In order to fix this, Company A has to assign the patent back to you and then you have to assign it to Company B.
In the last example, let's say you've filed a CIP application to an existing patent application. If the original assignee does not have right to the improvements in the CIP application, then a new patent assignment would have to specify that the improvements are owned by another assignee.
A lot goes into an assignment agreement and it is pretty straight forward once you get the hang of it. But if you make a mistake, most mistakes are correctable so long as the parties' intent is clear and you make the correction promptly.