The correct answer to this open question is the following.
Justice is the act to give people what it is appropriate, according to their necessities, work, perseverance, and commitment. Justice must maintain a fair opportunity for people getting what they want and deserve, always under legal circumstances.
The role Justice plays in determining what ought to be done about global poverty is that it has to promote a fair playing field for countries to trade under even circumstances, never granting advantages to the rich countries over the poor ones. Justice will allow fair trade and work opportunities when competing in open markets, so poor countries could have a real chance of benefiting from commerce and foreign investment.
Rich countries should not exploit poor countries, and they have to allow the proper scenario so people can have their basic needs covered.