We tend to think of judgment as the eternal judgment and the sorting of sheep to the right and goats to the left at the return of Jesus Christ. While this ultimately comes into play, we first need to examine some elements of judgment in the "here and now" rather than the "there and then." For the converted Christian, judgment is now on the house of God (I Peter 4:17).
As used in Matthew 23:23 as a weighty matter, "judgment" is from the Greek word krisis, meaning "decision for or against" and suggesting a tribunal or formal judgment. It implies "justice." Justice has several meanings, the first of which is "impartial adjustment of conflicting claims or assignment of deserved punishment or reward." More simply, when a conflict arises among people, justice is administering what is just - "factual, reasonable, faithful, morally upright, good, fair, righteous, impartial, and legally correct."
The Pharisees took one element of that definition - the "legally correct" part - and based their relationships with others on it, conveniently deleting fairness, impartiality, reasonableness, etc. from their thinking. Christ wanted them to be legally correct, for it is part of proper decision-making, but there is more to it than that!
The Weightier Matters (Part 1): Introduction