This political cartoon is supporting the Youth Criminal Justice Act. Lets look at the details.
The young boy seen in this political cartoon is in jail with an evidently older male. They are both wearing a sign that says "theft" suggesting that they were jailed because they stole something. The young boy looks uncomfortable sitting next to the man, who looks tough and is smoking.
The calendar behind the the two people show that it's March, 1902. At this time, the YCJA was not created and children 14+ were charged in adult courts and served adult sentences. They could be hanged, whipped, or imprisoned alongside other adult criminals. This is why the young boy wishes for justice for young criminals like him. They both committed the same crime, but despite the age difference, they're facing the same consequences.