Why UN slavery resolution won’t be enough

Slavery declared the gravest crime against humanity.

Slavery has been declared the gravest crime against humanity in a United Nations resolution. Argentina, Israel, and the United States were the only countries that voted against it, with many others abstaining. So what does this resolution mean, and why won’t the countries that built their wealth on slavery agree to a path for justice? Al Jazeera’s Marthe van der Wolf explains.