Does Hebrews 7:12 say that the Law has changed?
Answer: Yes, the Law has changed, and, this has necessarily occurred, exactly as it reads in English.
We do not need to linguistically decipher Hebrews 7:12 to understand this fact. Suppose we reiterate the passage in question for reference (including Heb. 7:11, NASB):
Hebrews 7:11-12: "Now if perfection was through the Levitical priesthood (for on the basis of it the people received the Law), what further need was there for another priest to arise according to the order of Melchizedek, and not be designated according to the order of Aaron? 12For when the priesthood is changed, of necessity there takes place a change of law also."
Aaron's name appears in verse 11 because he is inextricably linked to the Levitical priesthood: they are one and the same. On the other hand, Christ is obviously not a product of that priesthood, but is of the order of Melchizedek, that elusive figure mentioned in Psalm 110 as many of us have come to understand.
It should, therefore, be clear that God never intended the Messiah would descend through the bloody, imperfect, Levitical system to define His priestly status. The revelation by David reads as follows:
Psalm 110:4: "The LORD has sworn and will not change His mind, 'You are a priest forever According to the order of Melchizedek.'”
God's perfect law would be instituted by Christ. If this is not true, what then is the point of any new system arising out of an entirely separate priesthood? Because the intended audience of the Letter is the Jews, it should be plain enough that those who accepted Christ might be in danger of reverting back to Judaism. Thus, the need to carefully distinguish between the Mosaic Covenant, and the Covenant of Christ, one of a different priestly order entirely.
Perfection, in God's eyes, is when we are allowed to commune with Him. All saints are "priests of God" (1 Pet. 2:9), and are thus able to speak directly through the High Priest, Christ, to God in prayer without the need of any other mediator. Such was never the case with the Aaronic priesthood. This was an order designed to keep the people at a distance from God, one to emphasize their unworthiness — unlike the saints who are continually cleansed of all sin (1 Jn. 1:7), and all unrighteousness (1 Jn. 1:9) before God.
As well, under the Levitical arrangement, people were forbidden to enter the sacred areas of the Tabernacle/Temple. Even the priests themselves were unable to approach the Holy of holies with the exception of the high priest, and he alone but once a year. Thus, there could be no flawless fulfillment in that system, one which demanded another, perfect structure, one which demanded the ascension of another, higher order. Here, we should not overlook the words of the apostle Paul:
Galatians 3:21: "Is the Law [of Moses] then contrary to the promises of God? May it never be! For if a law had been given which was able to impart life, then righteousness would indeed have been based on law."
Followed by this:
Galatians 3:23-24a: "But before faith came, we were kept in custody under the law [of Moses], being shut up to the faith which was later to be revealed [in Christ]. Therefore the Law [of Moses] has become our tutor to lead us to Christ..."
These passages are emblematic of the enormous distinction between the Law of Moses (the Old Covenant) and the Law of Christ (the New Covenant) — Christ being our High Priest of the order of Melchizedek before God. Not only was the priesthood changed but so too was the entire Mosaic system upon which all else rested:
Matthew 27:50-51: "And Jesus cried out again with a loud voice, and yielded up His spirit. And behold, the veil of the temple was torn in two from top to bottom; and the earth shook and the rocks were split."
This was as dramatic an end to the Law of Moses, the Old Covenant, or the Levitical priesthood, as anyone could ever imagine. Not only did the priesthood cease to exist, but with its fall the entire Mosaic institution likewise collapsed along with it.
Some will vehemently disagree with this assessment, instead choosing to believe that the change was minor, where only the ceremonial or ministerial aspects were abolished. But this is a mistake.
However we decide to translate Hebrews 7:12, there can simply be no doubt that the Mosaic order — YES, including the Decalogue (Ten Commandments), was reinstituted in another form upon the inauguration of the new priesthood, one in which all saints partake as priests (cf. 1 Pet. 2:9, and a temple: 1 Cor. 6:19).
This is particularly evidenced by Jesus' Sermon on the Mount, in which He repeatedly enumerated many of the Ten Commandments beginning with "You have heard it said..." while replacing them with His new commands (paraphrased):
"You have heard it said":
"You shall not commit murder, but he who hates his brother has committed murdered in his heart" (Matt. 5:21-22).
"You shall not commit adultery, but he who lusts in his heart has committed adultery..." (Matt. 5:27-28).
"He who divorces his wife and marries another commits adultery" (Matt. 5:31-32).
"You shall make no false vows... But I say make no oath at all" (Matt. 5:33-37).
"An eye for an eye... turn the other cheek" (Matt. 5:38-39).
"You shall love your neighbor and hate your enemy... love your enemies, pray for those who persecute you" (Matt. 5:43-44).
The list is long indeed. The 613 laws and ordinances under the Mosaic regime have been superseded by a much stricter set of laws that comprise the Law of Christ, or the Law of Liberty, or the Royal Law: there are other equivalent designations of the Perfect Law of Christ.
Christ nailed the Decalogue to the Cross (Col. 2:14), by reaffirming it through His Own commandments (a tiny few listed above). The new laws are far more comprehensive than anything written in the Old Testament. I am trying here to preempt someone from suggesting the foolish notion that since the old law has been "taken out of the way", we may, therefore, murder, commit adultery, steal, lie, etc.
It should be obvious that we can do none of those things; all of Christ's commandments are much more demanding and all-encompassing than those in the Law of Moses. So, no, we cannot murder, commit adultery, steal, lie, and so on.
Suppose we consider the first transgression in the list above: Murder. In the O/T, a physical murder had to occur for the commandment to be broken. In the new, however:
Matthew 5:22: “But I say to you that everyone who is angry with his brother shall be guilty before the court; and whoever says to his brother, ‘You good-for-nothing,’ shall be guilty before the supreme court; and whoever says, ‘You fool,’ shall be guilty enough to go into the fiery hell" (emphasis added).
Are these statements fearful enough to get someone's attention? They certainly should be! How are they not perilous well beyond anything Moses ever wrote? Yes, Christ superseded the Decalogue — with far stricter, more rigorous laws! Not only are we constrained against sinful acts, but those previous commands have been extended and enhanced to the point where merely desiring something once condemned by physical action now has eternal consequences when committed in one's mind!
Yes, indeed, there was a definite change not only in the Law, but of the entire system upon which the Levitical priesthood was founded.