Are survivors' Social Security benefits liable to garnishment by the government to satisfy defaulted student loan debts?
Yes. The Debt Collection Improvement Act of 1996 (31 U.S.C. Section 3716(c)(A)(i)) now allows federal government agencies to offset Social Security benefits to collect debts such as student loans. Formerly these benefits were totally exempt; now you're left with a maximum exemption of $9,000 each year.