Can an assignee of a part interest in a patent application prevent other parties from accessing the application?

No, an assignee of a part interest in a patent application cannot prevent other parties from accessing the application. According to MPEP 106, the assignee of a part interest may not control prosecution of the application to the exclusion of the inventor or other assignees. This means that all parties with an interest in the application have the right to access and inspect the application file.

The USPTO recognizes the rights of all interested parties and ensures that no single party can restrict access to the application information. This policy promotes transparency and fairness in the patent examination process.