I am currently on sabbatical after receiving tenure and a position at another university opened up that I am interested in and they are interested in me as well. I'm wondering what is the general policy if a tenured professor were to leave during their sabbatical? Is it expected/required that they return for another semester or another year? Is there anything legally binding them to return or pay some part of their salary back? To provide more context, I am a tenured Associate Professor in the United States.
I suspect that you have a contract that spells this out. Accepting a sabbatical (with pay) often/normally requires that you agree to spend an additional year if the sabbatical lasts a year.
But every university (system) is different in the US. Explore it with your department head (or HR) if you can't check otherwise.
Unpaid sabbaticals and shorter ones may be different, but it is unlikely that you didn't make some formal agreement when you accepted the leave.
And, there may be an option to pay back the funds you accepted in order to free yourself. Hard to manage, of course.