Anyone who speaks against his brother or judges him speaks against the law and judges it.
What is “speaks against” – or slander here. I mean James is clearly speaking forcefully to his brothers. How is this not speaking against or judging?

RJS, tough one for me. But I think we have to assume James is not doing what he is teaching against. Once we admit that orientation, then we can conclude that it has to do with setting oneself up as God the Judge and damning others. That means, as well, that accurate judgment and discernment are permissible and inaccurate judgment and discernment aren’t.
It is too easy to use this text casually; it is also too easy to dismiss it.
But it’s a tough one coming from an author (James) who uses harsh words.

peelingdragonskin.wordpress.com
RJS-
Excellent question. The answer: avoid the “bad speaking against”; embrace the “good speaking against.”
But seriously, I think Dallas Willard’s discussion of this issue in the Divine Conspiracy was very helpful. The bad version is related to “condemning” and “contempt.” Ultimately, I am not sure you can say much more than that it takes Spirit led wisdom to know the difference.

A distinction has to be made between a person
(brother) who is present or one who is not present.
This doesn’t seem obvious, because James doesn’t
discuss this, but it has been clarified by other
Christians. John Wesley’s “The Cure of Evil
Speaking” comes to mind(One of his 52 standard sermons).
It is an interesting personal experiment to focus on
who and where you will hear someone speak poorly
of another behind that person’s back. The teacher’s
lounge and church porches, imho, are prime places.
Teachers usually adopt a traditional, liberal, or
communicative style. And I mean teach in a kerygmatic style,
or detached from a relative point of view, or to bring
out all the views and even try to integrate. The point is
that to teach communicatively you will not gossip, and the views of the people participating will not be disparaged. Otherwise it is not, by definition, the style you are using.
And isn’t it interesting to notice the identities
of teachers who adopt the different styles, or to look at oneself
and notice on which topics we use the different styles. When
we get preaching the party line, or very detached is when
we are most susceptible to judging and slandering.