Legal standards are not limited to the determination and interpretation of each individual because then there would be no universal understanding of what is lawful. For example, say if one person says it is wrong to steal but another thinks there is nothing wrong in stealing. Both people in this situation would be right if legal standards could be determined by each person. However, this is impossible for God makes the laws. If laws were not made by God, there would be chaos everywhere. Everyone would be able to do whatever they wanted to because they decide whether what they're doing is okay or not. To conclude, this verse is all the evidence we need as Christians to know that the Almighty God has created and given us legal standards to follow and carry out.
"You must obey my laws and be careful to follow my decrees. I am the Lord your God."
-Leviticus 18:4