James 4:11

Speak not evil one of another, brethren
The apostle here returns to his former subject, concerning the vices of the tongue, he had been upon in the preceding chapter, ( James 3:6-10 ) , and here mentions one, which professors of religion were too much guilty of, and that is, speaking evil one of another; which is done either by raising false reports, and bringing false charges; or by aggravating failings and infirmities; or by lessening and depreciating characters, and endeavouring to bring others into discredit and disesteem among men: this is a very great evil, and what the men of the world do, and from them it is expected; but for the saints to speak evil one of another, to sit and speak against a brother, and slander an own mother's son, is barbarous and unnatural.

He that speaketh evil of his brother, and judgeth his brother,
speaketh evil of the law, and judgeth the law;
he that is a talebearer and backbites his brother, his fellow member, and detracts from his good name and character, and takes upon him to judge his heart, and his state, as well as, to condemn his actions, he speaks evil of the law; and judges and condemns that, as if that forbid a thing that was lawful, even tale bearing and detraction, ( Leviticus 19:16 ) , or by speaking evil of him for a good thing he does, he blames and condemns the law, as though it commanded a thing that was evil; and by passing sentence upon his brother, he takes upon him the province of the law, which is to accuse, charge, convince, pronounce guilty, and condemn:

but if thou judge the law, thou art not a doer of the law;
as is a duty, and would best become:

but a judge;
and so such a person not only infringes the right of the law, but assumes the place of the Judge and lawgiver himself; whereas, as follows,