Cosigner's Rights

Has anyone made demand upon you yet that you pay off the loan on his behalf? Or are you just worried about that possibility?

There are all sorts of different personal guarantees. The rights of the guarantor very much depend on the exact terms of the written document he signs.

Some guarantees are tied to another document's terms -- for example, so that the effective term of the guarantee lasts as long as the effective term of the loan, so that the guarantee is extinguished early if the loan is pre-paid early, or the obligation to pay on the guarantee is triggered if the loan remains unpaid at the end of the loan term. Some guarantees are written to automatically apply to extensions of the loan.

Some guarantees are tied not to particular documents, but to particular PEOPLE or COMPANIES: For example, sometimes to persuade a bank to loan to a corporation he owns, the owner of the corporation will give the bank a personal guarantee that covers all debt that the corporation incurs in the future. For those sorts of guarantees, the guarantor may be able to simply give written notice that he will not guarantee any further debt after the date of the notice -- in which case the bank will presumably stop making new loans.

The guarantor (you) has rights against the principal (your girlfriend's brother) if he fails to repay the loan or otherwise puts it into default in a way that causes the lender to turn to you to make good on the guarantee. Some of those rights are contractual, but some of them may also be "common law rights" established by court decisions over the years. The fact that he's moved to another state may make your rights harder to enforce, but him moving doesn't exterminate those rights; and indeed, you may still be able to sue him, if necessary, in your home state (where he also lived, I presume, when the loan and guarantee were first made).

To answer your question, any lawyer would need more information about your circumstances, and he or she would probably want to review the specific terms of the guarantee(s) you signed. I doubt it's going to be practical for you to get much more guidance about this through an internet service like this one -- you probably do need to consult with a flesh-in-blood attorney in person.