How did the U. S. Constitution make sure the government had enough power to act, but also protect the people's rights?

Aresearcher is studying women recently admitted to a state prison. all potential subjects must have children under the age of five. research subjects will be given a basket of toys to use at their children’s first visit that the children can then take home. in assessing this proposal, the irb needs to determine that the toys are: age appropriate. not an excessive incentive. educational. of high quality.