In the US, people are jailed as a result of trials in which they had no lawyer.

Often this is for nonpayment of child support.

It is legitimate to make fathers with money provide some of that for their children. It is nonsensical to do this to poor people; they can't pay what they don't have.

The right solution for this problem is (1) to improve the welfare system so that no child has to grow up in poverty, father or no father, and (2) help and encourage people that can't afford to raise children properly to use reliable birth control.