There are more modern translations that now translate the verse more accurately. Let me present more modern and acceptable translation of this verse.
Note that I interpret the vav conversive as subjunctive.
In Amos 5:24, the Hebrew says
ויגל כמים משפט וצדקה כנחל איתן
ויגל
| should roll (as in waves) |
כמים
| like water |
משפט
| sentencing-judgment |
וצדקה
| and righteousness |
כנחל
| like a river/stream |
איתן
| steadfast |
Therefore,
Judgment sentencing should roll like waves of water, and righteousness like a steadfast steady river.
This verse, in Hebrew says that,
Why does it mean that Judgment should be sentenced like rolling waves?
It might take a mighty force, or it might take a small still voice in the face of impeding adversity, to be a steady flowing river or stream.
What might interest you are the words [משפט] and [צדקה].
[משפט] actually means a linguistic sentence, or verbalisation.
This is another of the English words that had been influenced by the Hebrew of the Bible. To sentence a legal judgment, is to verbalize the judgment in succinct comprehensive language.
[צדקה](tsedakah) being righteousness, is also often used to imbue charity to the poor. Therefore, our tax dollars used for helping the poor in sustenance and furnishing them with education is a commanded righteousness.
Sedakah in Arabic, which has the same meaning as in Hebrew, also uses the word righteousness in similar manner. When you move among Arabs or Muslims, you would also often find them using the word sedakah sloganeering for contributions to the impoverished. Apparently therefore, Jews, Arabs and Muslims share the same concept on righteousness.
You might also take note that [איתן](eithan) is the origin of the English name Ethan - steadfast.
