The latest security-inspired bill to go through Parliament fundamentally alters Australian citizenship laws, so here is a primer for all the new and interesting ways you can now become unAustralian, writes Michael Bradley.

Congratulations, dual citizens: you can now become unAustralian in new and interesting ways. The Australian Citizenship Amendment (Allegiance to Australia) Bill will pass through Parliament this week. Almost nobody cares about this, but we should record for posterity that the content of Australian citizenship has just been fundamentally altered.

Who can lose their citizenship?

Any Australian citizen aged 14 or over, who is also a citizen or national of another country, can lose their Australian citizenship. Whether you're a foreign citizen is generally easy to identify. What a "national" of a foreign country is, I don't know. That's never been defined.

More than six million Australians were born overseas, and an estimated four or five million more were born here but hold dual citizenship. So, under this law, more than 10 million Australians are eligible to lose their citizenship.

Is this how all those Kiwis have been getting kicked out?

No, different law. The Immigration Minister has power to deport people who have never acquired Australian citizenship, under a "character" test. He's been using that lately to detain and deport hundreds of New Zealand citizens after they've served sentences for crimes committed here. He can't use the same mechanism on anyone who is an Australian citizen.

How does it work?

Four categories of conduct can cause you to lose your citizenship. First (this one isn't new), if you fight for a foreign country at war with Australia. Secondly, if you fight for a declared terrorist organisation outside Australia. If any of the surviving Australians serving with IS are foreign citizens or nationals, then they'll never be coming back (academic, since their passports had already been cancelled).

Thirdly, if you are convicted of certain crimes and sentenced to at least six years in prison, then the minister can take away your citizenship and you'll be deported when you've done your time.

Finally, you can automatically revoke your own citizenship by engaging in certain types of terrorism-related conduct. No criminal charge or conviction required.

Which crimes?

The final list of deportation-worthy crimes is shorter than originally proposed. Here's what you should avoid:

Terrorist acts (including recruiting, training, funding);

Terrorist acts (including recruiting, training, funding); Treason or espionage against Australia;

Treason or espionage against Australia; Overthrowing the government or sabotaging military stuff;

Overthrowing the government or sabotaging military stuff; Being a "foreign fighter" (stay away from areas declared by Julie Bishop as no-go zones).

The most controversial offences didn't make it onto the final list. You won't lose your citizenship if you're convicted of advocating terrorism or of urging force or violence against a group distinguished by race, religion, nationality, ethnic origin or political opinion. That's good news for the heroes of talk-back radio.

Automatic renunciation - how will I know?

You'll know when the minister tells you, which he'll do when ASIO tells him that you've committed one of the types of conduct that triggers the renunciation of your citizenship. It's like saying "I divorce thee", except in actions not words.

The conduct in question is all the terrorism stuff. The big change in the final version of the law is that there's a strict intention requirement. You have to both do the act (for example, send money to a terrorist organisation), and have the intention of advancing a political, religious or ideological cause and of intimidating a government or the public. So, in theory, you can't lose your citizenship by accident.

Did they end up making it retrospective?

Yes, but only for criminal convictions. If you were convicted of one of the listed offences within the past 10 years, and sentenced to at least 10 years in prison, then when you get out the minister can revoke your citizenship.

If you believe (as I do) that loss of citizenship is punitive, then this measure infringes two basic legal principles: that the executive arm of government is not empowered to impose punishments (that's the exclusive right of the courts); and that the potential punitive consequences of a criminal act should be known at the time you commit it.

Mind you, that doesn't mean the law is necessarily invalid. The High Court has never directly considered whether loss of citizenship is a punishment. If asked, I suspect it will say that it isn't. I'm just saying I think that'd be wrong.

Constitutional challenge coming?

Yes, inevitably. The likely target is the automatic renunciation provision. If Immigration Minister Peter Dutton does go hunting for somebody who he can say has renounced their citizenship by conduct, then a High Court challenge to the validity of that outcome will follow.

My view is that the provision is unconstitutional for two reasons.

First, it involves an exercise of judicial power by the executive. Only the courts are allowed to decide criminal guilt and impose punishments. While this law has been carefully crafted to look like nobody is doing that (the idea is that you do it to yourself), the reality is that the minister or somebody reporting to him has to decide whether or not you have physically committed the requisite act, and whether or not you had the requisite intention when you did it. These decisions involve the exercise of judgment. The outcome is that you can effectively be found, by the minister, to have committed a crime, without ever being charged or convicted of it.

Secondly, the law exceeds the Commonwealth's legislative power. The Parliament has power to make laws with respect to "aliens", who are people owing an allegiance elsewhere than Australia. Taking away a person's Australian citizenship necessarily renders them an alien. A person born in Australia could in some circumstances also be a foreign citizen. Can the Parliament turn that person into an alien, when nothing they ever did was consistent with having a foreign allegiance?

I think the High Court should knock this law off. But look, I just wrote two paragraphs on it, compared to the few thousand paragraphs of submissions that will be involved in the legal challenge when it comes. It's going to be a big and super-complicated fight, of interest to not even most lawyers.

Can I get back to the cricket now?

Yeah, as you were. The great unknown here is whether this new law will ever be used. Most of our national security laws have not.

Malcolm Turnbull has made it clear enough that he thinks elements of this law are stupid, so it'll be interesting to see whether he forces it to the backbench to stew in irrelevance with the guy who thought it up in the first place.

Michael Bradley is the managing partner of Marque Lawyers, a Sydney law firm, and writes a weekly column for The Drum. Follow him on Twitter @marquelawyers