A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
2 Chronicles 19:1
ch2 19:1JEHOSHAPHAT VISITS HIS KINGDOM. (Ch2 19:1-4)
Jehoshaphat . . . returned to his house in peace--(See Ch2 18:16). Not long after he had resumed the ordinary functions of royalty in Jerusalem, he was one day disturbed by an unexpected and ominous visit from a prophet of the Lord [Ch2 19:2]. This was Jehu, of whose father we read in Ch2 16:7. He himself had been called to discharge the prophetic office in Israel. But probably for his bold rebuke to Baasha (Kg1 16:1), he had been driven by that arbitrary monarch within the territory of Judah, where we now find him with the privileged license of his order, taking the same religious supervision of Jehoshaphat's proceedings as he had formerly done of Baasha's. At the interview here described, he condemned, in the strongest terms, the king of Judah's imprudent and incongruous league with Ahab--God's open enemy (Kg1 22:2) --as an unholy alliance that would be conducive neither to the honor and comfort of his house nor to the best interests of his kingdom. He apprised Jehoshaphat that, on account of that grave offense, "wrath was upon him from before the Lord," a judgment that was inflicted soon after (see on 2Ch. 20:1-37). The prophet's rebuke, however, was administered in a mingled strain of severity and mildness; for he interposed "a nevertheless" (Ch2 19:3), which implied that the threatened storm would be averted, in token of the divine approval of his public efforts for the promotion of the true religion, as well as of the sincere piety of his personal character and life.
2 Chronicles 19:4
ch2 19:4he went out again through the people--This means his reappointing the commissioners of public instruction (Ch2 17:7-9), perhaps with new powers and a larger staff of assistants to overtake every part of the land. The complement of teachers required for that purpose would be easily obtained because the whole tribe of Levites was now concentrated within the kingdom of Judah.
2 Chronicles 19:5
ch2 19:5HIS INSTRUCTIONS TO THE JUDGES. (Ch2 19:5-7)
he set judges in the land--There had been judicial courts established at an early period. But Jehoshaphat was the first king who modified these institutions according to the circumstances of the now fragmentary kingdom of Judah. He fixed local courts in each of the fortified cities, these being the provincial capitals of every district (see on Deu 16:18).
2 Chronicles 19:8
ch2 19:8TO THE PRIESTS AND LEVITES. (Ch2 19:8-11)
set of the Levites . . . priests, and of the chief of the fathers of Israel--A certain number of these three classes constituted a supreme court, which sat in Jerusalem to review appellate cases from the inferior courts. It consisted of two divisions: the first of which had jurisdiction in ecclesiastical matters; the second, in civil, fiscal, and criminal cases. According to others, the two divisions of the supreme court adjudicated: the one according to the law contained in the sacred books; the other according to the law of custom and equity. As in Eastern countries at the present day, the written and unwritten law are objects of separate jurisdiction.