In his lectures on jurisprudence Smith notes the importance of the law of habeas corpus in protecting the liberty of subjects against oppression by the king:
The Habeas Corpus Act is also a great security against oppression, as by it any one can procure triall at Westminster within 40 days who can afford to transport himself thither. Before this Act the Privy Councill could put any one they pleased into prison and detain him at pleasure without bringing him to triall. Now no one can be imprisoned anywhere but in the county gaol or the nearest to it where the crime is said to have been committed; he cant be sent out of Britain to Jersey, | Guernsey, or the plantations, that is, alway<s> within the extent of the Hab. Corp. Act.—This sufficiently secures the liberty of the people; for tho many could not afford the expense, yet it is not such who will be in greatest danger from the king. The rich and powerfull are most obnoxious to his displeasure; tis rich and not poor folk who are sent to the Bastile in France. No judge can oppose the Habeas Corpus Act; infamy and a high penalty are the punishment which attend it. No influence of the king could ever induce them to make any such attem<p>t. And so strict is this Act that in the time of rebellions or other exigencies of the state, when it is necessary to imprison without such speedy triall, it is commonly taken off for 6 months. But it will never be allowed to be reppealed, as that would destroy in a great measure the liberty of the subject.
About this Quotation:
On Wednesday, March 9th, 1763 Adam Smith lectured his students at the University of Glasgow on the importance of the Habeas Corpus Act. He argued that the right to appear before a court in person, to have the charges against one read out in a public court, to have legal representation, and the chance to refute the charges, is a key defence against any potential tyranny of the King. He concluded confidently that this legal right “sufficiently secures the liberty of the people.” Smith was not the only classical liberal to ardently support this right. We would also recommend the writings of Coke and Voltaire in this regard.