A law professor who helped stop fathers fleeing to the US to avoid paying child maintenance says he is delighted with the breakthrough.
Aberdeen University’s Paul Beaumont played a key role in lengthy negotiations over White House support for an international agreement.
His efforts were rewarded when President Barack Obama ratified the Hague Convention on International Recovery of Child Support.
It means fathers who live in the US but do not pay child support for children living in other countries can now be forced to do so.
American ratification opens the door to millions of pounds of support – often for families in countries with no welfare state as a back-up.
Experts hope it will encourage other states to sign up.
The EU was already among the signatories.
Professor Beaumont, who has been involved in the convention since discussions first began in 2003, said it was a “landmark step”.
“The scale of the impact of this is huge, and it will improve the lives of hundreds of thousands of people,” he said.
“On a personal level I’m delighted because the negotiations went on for a long time and ratification was never guaranteed.
“To get a final agreement was very satisfying, and a testament to the hard work of everyone involved.”
He added: “There are plenty of scenarios where the failure of the father to pay means that the children are living in really bad situations.
“The convention also helps ease the financial burden on participating states that provide welfare support to families in situations where fathers are failing to fulfil their obligations.”