Hayek on American Constitutionalism

Hayek:

When Montesquieu and the framers of the American Constitution articulated the conception of a limiting constitution that had grown up in England, they set a pattern which liberal constitutionalism has followed ever since. Their chief aim was to provide institutional safeguards of individual freedom; and the device in which they placed their faith was the separation of powers. In the form in which we know this division of power between the legislature, the judiciary, and the administration, it has not achieved what it was meant to achieve. Governments everywhere have obtained by constitutional means powers which those men had meant to deny them. The first attempt to secure individual liberty by constitutions has evidently failed. [Law, Legislation and Liberty, Volume 1: Rules and Order, p. 1]

Does this seem correct? If so, are there any means by which limited government might be achieved?