Psalm 43 begins with the writer asking God to “vindicate” him. Verse one uses a legal metaphor common in the prophets to picture the writer and his enemy before God as his judge. About 40% of the occurrences of the word שפט have God as the judge, nine times the verb is used as a noun to describe God as the “judge.” Sometimes God is called on to judge between two people who are at odds. The phrase “defend my case” is also the language of a lawsuit. The verb ריב and the related noun are both used in the context of someone taking someone to court to sue them. The psalmist is picturing himself going to the city gates of his town and standing before the elder of the town, a king’s magistrate. In order to get real justice, perhaps he has to go to the king himself and plead his case.
The psalmist is calling on God to “do justice” in this case. In a human court, the goal is to hear the evidence on both sides of that case and let the judge decide who is “right” and who is “wrong.” If God is the judge, the Psalmist can be assured of justice because God is ultimately just in his nature.
Just as in a human court, the psalmist offers evidence against his enemy. First, his enemy is “an ungodly nation.” The noun is simply nation (גּוֹי), although in the context most translations render the word as referring to non-Jewish, pagans or heathens. In the next Psalm, for example, the word is used for the nations the Lord drove out of the land (44:2).
Second, they are not faithful . One of the cornerstone virtues in the Hebrew Bible is faithfulness(חָסִיד). The word does not mean “full of faith,” as if it is a synonym for “a believer.” The idea of faithfulness in the Hebrew Bible is an action, one “does faithfulness.” The word is frequently used to describe those who abuse the poor and needy, to be “unfaithful” to the covenant (Mic 7:2).
Third, they are unjust. The noun מִרְמָה has the connotation of being a fraud, a trickster. The writer’s adversary tries use some sort of subterfuge to get his way. The word describes Jacob stealing his brother’s blessing (Gen 27:35) and the actions of Simeon and Levi when they made a false covenant with the king of Schechem (Gen 34:13). Micah 6:11 uses the word to describe dishonest weights, which look like the real thing but intend to steal from the unaware. The word is among the many things listed in Psalm 24 which qualifies someone for going up to the Holy Hill of God to worship (someone who does not swear deceitfully).
Last, they are oppressing the writer (v. 2). The noun לַחַץ does not appear frequently in the Hebrew Bible, but it does appear in each of Psalms 42-44 (and only in this series of Psalms in the Psalter). Exod 3:9 and Deut 26:7 use the noun to describe the oppression Israel faced when they were in Egypt. The verbal form of the root is used in a number of other passages which describe foreign oppression Judg 2:18, 4:3, 6:9, 10:12; Isa 19:20(, oppression which is sometimes a punishment for covenant unfaithfulness )Amos 6:14,
This description of an enemy is applicable during the life of David, either when he was running from Saul or later from Absalom. But it is also generic enough that this Psalm would be a great comfort for someone living outside the land during the Exile – when has Israel not been oppressed by a faithless enemy?
This psalm is a promise that God does in fact judge fairly, he will vindicate his people and render justice.