Daniel 6:8 - Clarke's commentary and critical notes on the Bible

Now, O king, establish the decree, and sign the writing, that it be not changed, according to the law of the Medes and Persians, which altereth not. According to the law of the Medes and Persians - I do not think that this is to be understood so as to imply that whatever laws or ordinances the Medes or Persians once enacted, they never changed them. This would argue extreme folly in legislators in any country. Nothing more appears to be meant than that the decree should be enacted, written, and registered, according to the legal forms among the Medes and Persians; and this one to be made absolute for thirty days. The laws were such among this people, that, when once passed with the usual formalities, the king could not change them at his own will. This is the utmost that can be meant by the law of the Medes and Persians that could not be changed.