Mr. Layton has raised an interesting issue, and the key, I think, to understanding revolves around how one defines one's terms. I don't think one shoulod take the approach, in a discussion such as this of simply saying a "liberal" is defined as, or a "conservative" is defined as whatever.
Mr. Layton suggests that the constitution is a liberal document and that liberalism suggests, as I believe he is pointing out, that "to have liberty one must grant liberty."
So, let us start with the premise that liberalism involves the granting of liberty. How then, by this definition, do today's "liberals" stack up. As has been pointed out already in this thread, these individuals do not fare very well by this standard.
I would like to posit the thought that todays "liberals" are not at all "liberal." I would contend that a better term to describe these individuals would be "antilibertarian."
We must be very careful not to accept an individual's label, as applied by him/herself as definitive of his/her actual philosophical or political bent. If a giraffe were to call itself an elephant, that would not make it an elephant.
Our nation's recent political history is very enlightening in this regard. There was a time, in the not distant past, when certain politicians openly proclaimed themselves as "liberal." this was a time when such a label enjoyed a certain popularity. But, times change, and recently that apellation has lost its political luster to a considerable degree. So, individuals of the political bent that once proclaimed proudly of their liberalism switched to referring to themselves as "progressive" or "centrist" or "moderate." They ran in political terror from the "L" word. Realistically, they had not undergone a philosophical metamorphosis; they had just undergone a name change.
As the Bard said, "What's in a name?"
At the present time, those who most aptly fit the "liberty" criterion are those commonly referred to as "conservative." Once, proclamation of this title would have been the political equivalent of leprosy.
As a nation, we've been for a very long time hung up with labels that, in my opinion, have come to mean very different things from when they were first applied. Their continued use, I believe, has poisoned the well of political discourse to the point that we're recreating the Tower of Babel.
I don't know, perhaps one answer is to adopt more meaningful terms such as "prolibertarian" and "antilibertarian." Not that I think we ever will. No politician would ever want to adopt a label such as "antilibertarian," or "anti" just about anything for that matter, no matter how fitting it might be.
In any event, it does not seem very helpful, or appropriate, to adopt 18th century definitions for terms in use today, especially as those terms, as labels, do not actually describe the behaviors of those who wear them. It is quite clear to me that todays "liberals," whatever they call themselves, are in no way champions of liberty.