Most US laws regarding convicted felons voting rights persist even after they've served their sentences.
And if you consider the fact that black men are disproportionately more likely to be jailed, that's where the suppression angle comes into play.
Yes, I completely get that, but as I said I'm just not sure it's that simplistic. I'm 100% sure that it's an immensely pleasing bonus to many, but I'm not entirely sure it was designed purely to stop black votes. How long has it been law? And the same question for other countries too?