When Or Becomes And

Do not speak evil against one another, brothers. The one who speaks against a brother or judges his brother, speaks evil against the law and judges the law. But if you judge the law, you are not a doer of the law but a judge.
James 4:11

Notice the change of conjunction in the two following clauses.

The one who speaks against a brother or judges his brother, speaks evil against the law and judges the law.

I speak evil of my brother because I've judged him in my heart.

When I've only judged my brother in my heart, even if words never leave my mouth, my heart has already spoken evil of the law (and in essence my heart has already spoken evil of my brother).

In other words, Scripture tells us that God views speaking evil of my brother and judging my brother in my heart as one and the same.

...out of the abundance of the heart his mouth speaks.
Luke 6:45