Q. Our product makes use of the NCBI source code, and we did changes and additions to that version of the NCBI code to better fit it to our needs. Can we copyright the code, and how?

A. You can copyright only the changes or the additions you made to the NCBI source code. You should identify unambiguously those sections of the code that were modified, e.g. by commenting any changes you made in the code you distribute. Therefore, your license has to make clear to users that your product is a combination of code that is public domain within the U.S. (but may be subject to copyright by the U.S. in foreign countries) and code that has been created or modified by you.

Q. Can we (re)license all or part of the NCBI source code?

A. No, you cannot license or relicense the source code written by NCBI since you cannot claim any copyright in the software that was developed at NCBI as a ‘government work’ and consequently is in the public domain within the U.S.