By inserting the requirement for "allegiance to Australia" into the proposed citizenship laws, the Government is invoking an idea that hasn't really existed since medieval times, writes Michael Bradley.

Tony Abbott's language has become quite medieval lately, reframing the national security debate as a battle to the death between good (him) and evil (the Daesh death cult).

He described the proposed citizenship revocation law as a "modern form of banishment". So it's interesting to discover in that law the appearance of the concept of "allegiance to Australia". I've never contemplated that I had any allegiances other than to the Manly Sea Eagles. Is allegiance really a thing?

Section 33AA of the proposed law says that dual citizens will renounce their Australian citizenship if they act "inconsistently with their allegiance to Australia" by engaging in certain conduct. This is careful drafting and a novel legal concept - the idea that you can stop being Australian by choice, not by words but by actions. The insertion of allegiance is deliberate, and that's what I want to explore.

It has deep historical roots - we're talking Middle Ages. Back then, you were a King, or a lord, or a serf. The relationship between each level of the hierarchy was governed by reciprocal duties. If you were a peasant, you owed duties of fealty to your lord, and in return he was obliged to protect you. The English common law developed this further so that, if you were born in England, you were by birth a "subject" of the King and you owed a duty of allegiance to him. The allegiance was personal, absolute and permanent. You couldn't lose it or give it up.

The law evolved over time, as Europe changed from a landscape of constantly shifting monarchies and principalities towards the rigid borders of the modern nation states and migration became a big deal. The theory of permanent allegiance was thrown into disarray by the American Revolution, when a whole bunch of English subjects declared themselves an independent nation and said they were allegiant no more. The law slowly came around to accepting that allegiance isn't always such a permanent thing.

When Australia came into being in 1901, we were all still British subjects. In fact, there were no Australian citizens at all until 1948, when we finally became a nation independent of the United Kingdom. Our allegiance to the Queen of the United Kingdom was then transferred to the Queen of Australia. That remains the law today.

My surprise in learning that I owe allegiance to the Queen probably reflects what most locally-born Australians would think. The practical reality is that the Queen is our titular head of state only, and the Commonwealth of Australia is now a political entity that can do what it likes. At some point we will ditch the monarchy altogether and bring the law and realpolitik back together again. But in the meantime, the question remains: on what basis am I, a person born here, entitled to call myself Australian?

I thought it was simply my birth right. It turns out that there's no such thing. The Government is seeking to entrench the ancient legal fiction that, when I was born, I took on allegiance to my monarch, and the allegiance is what gives me the entitlement to live here. They've changed the identity of the beneficiary from the Queen to "Australia", and that's not just because they don't want to remind us that we're still a monarchy.

What's happening here is very subtle. The Government is seeking to co-opt the historical anachronism that we are all subjects, not free persons, and transport it into the modern context of the nation state. The intended result is the development of a new concept - that all Australians, whether born here or naturalised, owe an allegiance that is much deeper than we've ever understood.

The High Court, when it last looked at last looked at allegiance, reflected that what that actually means in practical terms has never been defined but was always a light burden. In reality, it means not committing treason - trying to kill the head of state, overthrow the government or fight for an enemy state. We've never conceptualised it as having more content than that, and over the centuries we have become more and more convinced that each of us, as an individual thinking person, has full freedom of thought and opinion, and very wide freedom of expression. The starting point these days is that we are free; any restriction on that by the state must be justified. It's the reverse of the medieval position.

The Government has shown its hand. It is attempting to redraw our relationship with Australia as a State, to elevate the State to a position equivalent to that of a medieval king, to which fealty is owed in return for protection from physical harm. The new citizenship law, by seeking to add an extremely long list of ways in which we can "renounce" our citizenship, is designed to make them a substantive part of our personal duty to the State. This is a very different thing from just calling them a crime. Losing your liberty is a very different thing from losing your identity as an Australian.

Before you discard this line of thought with the point that the law will only apply to dual citizens, remember this: people born in Australia can become dual citizens; and the draft law has been referred to a committee with the remit to consider whether it can be extended to people who aren't dual citizens but could be eligible to apply for foreign citizenship, as well as applying it retrospectively to past actions. The ultimate goal - don't be deceived about this - is that it will apply to all of us.

One thing's for sure: the Government's legislative program on national security is not being driven by thought bubbles. This is deliberate, and it will change our nation irrevocably.

Michael Bradley is the managing partner of Marque Lawyers, a Sydney law firm, and writes a weekly column for The Drum. He tweets at @marquelawyers.