Liberal Democrat ex-cabinet minister Michael Moore is introducing a backbench bill to make it a legal requirement that at least 0.7% of Britain's GDP is devoted to helping poor countries, in line with a United Nations target.
The coalition government agreed to the amount last year, but the promised legislation has so-far failed to materialise.
The 0.7% pledge, in line with the UN target, has previously had the backing of all three major parties, but this is the first time it will be enshrined in UK law.
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There is nervousness, anxiety and on the streets of Edinburgh fuelled by an atmosphere unlike anything seen before in recent UK politics.
However the vote goes, bonds of blood, history and geography mean the people of the Scottish borders will stay closely linked to England.
Alex Salmond could be hailed the future leader of a new country, but there is still no agreement on how an independent Scotland would work.