1st Year Law School Outlines: e book (electronic borrowing OK)

Law school e book,
- Look Inside! (electronic borrowing OK)

Excerpt:
An assignee’s interest vests as soon as he knows of the assignment, relies on it, or sues on it.

If an assignee is a donee who did not pay for the assignment to him, the original parties may change the contract at any time. But if the assignee a person who paid value the original contract cannot be changed if the assignment has vested.