11 Speak not evil one of another, brethren. He that speaketh evil of his brother, and judgeth his brother, speaketh evil of the law, and judgeth the law: but if thou judge the law, thou art not a doer of the law, but a judge.
12 There is one lawgiver, who is able to save and to destroy: who art thou that judgest another?
James here says we should not talk bad about people in any way. A lot of time we will begin saying something about someone and not realize we are judging them by what we say. By doing this we are saying we are better than the law itself and think we are above the law, and setting our self up as judge and there is only one judge and that is God. There is only one that gave the law and He can save those that repent from their sin and He will destroy those that do not, but He, God, is the the only one that can. Remember when Jesus ask the people, when they brought woman accused of adultery before Him, he who is without sin cast the first stone, they all had to leave. They had judged her but Jesus showed them who are we to judge. We are no better than anyone else except for the saving grace Jesus Christ and that still does not put us above others for us to judge them.
1 John 1:8 “If we say that we have no sin, we deceive ourselves, and the truth is not in us.”