Adam Clarke on Psalms 72:14

From deceit and violence - Because they are poor and uneducated, they are liable to be deceived; and because they are helpless, they are liable to oppression; but his equal justice shall duly consider these cases; and no man shall suffer because he is deceived, though the letter of the law may be against him.

And precious shall their blood be - If the blood or life of such a person shall have been spilt by the hand of violence, he shall seek it out, and visit it on the murderer, though he were the chief in the land. He shall not be screened, though he were of the blood royal, if he have willfully taken away the life of a man.