Those who follow only the letter of the law and ignore the spirit of the law fall into the trap of legalism. Legalism ultimately produces defeat. Such legalism brought condemnation from members of his own party and ultimately left a bad taste in the mouth of the general population. He was arguing the letter of the law, but ignoring the spirit of the law. Many Christians have done the same thing.
Legalism always leads to defeat.
That's why the Bible instructs us to live by the power of the Holy Spirit. When we live by the Spirit, we are not under the rule of the law. That doesn't mean that we ignore the law or violate the law. It simply means that we fulfill the deep purposes of the law. In other words we do the will of God from the depths of our hearts.