The older dollars had this printed on the front:
"This note is legal tender for all debts public and private, and is redeemable in lawful money at the United States Treasury, or at any Federal Reserve Bank"
Now they only say:
Legal tender does NOT make it "lawful money" A dollar "bill" or reserve "note" is just an elaborate IOU and a legal contract which they do not seem to want to honor.
We're trying to redeem this $100 note at the Treasury and we will let you know what happens.