Private student loans are subject to the defense of laches. Federal student loans are not.
The defense of laches asserts that a debt is unenforceable if there has been an unreasonable and harmful delay in the lender demanding payment.
The Higher Education Technical Amendments of 1991 eliminated the defense of laches on federal education loans. But, even prior to enactment of this repeal, the defense of laches usually did not apply to federal education loans because a federal education loan borrower has an affirmative obligation to notify the servicer of any changes in his or her address or telephone number.