Passed in the 1600s, laws aimed at distinguishing the social status of european indentured servants from that of african slaves were known as the:

They were known as the slave codes

There was a few of these laws passed and they were used to determine when and for how long and how would someone become a slave. This included things like looking at the status of a mother, or looking at the status of their religion, or anything similar, including differentiation between indentured servitude and slavery.