The Australian Constitution is silent on citizenship.

It gives the Commonwealth Parliament the power to make laws with respect to ³immigration and emigration² and with respect to ³naturalization and aliens².

But there is no specific power over ³citizenship².

This may be critical as to whether Prime Minister Tony Abbott can achieve his desire to legislate to give the Minister for Immigration the power to revoke the Australian citizenship of people engaged in terrorism.

Let¹s leave aside for the moment that it is just a grandstanding political stunt of little practical effect in deterring terrorist acts.

Let¹s look instead at what it tells us about the people who support these laws and whether these laws would survive constitutional challenge.

Significantly, the Constitution does not give the Federal Parliament a general citizenship power ­ a power to grant it and take it away. There is good evidence to suggest that the constitutional framers did this deliberately, fearing the Parliament might act to take citizenship away from people born in Australia.

Instead, the Parliament was given powers with respect to ³immigration and emigration² and ³naturalization and aliens².

That is much narrower.

The High Court has considered these powers in a lot of detail over the past

few decades.

It has been a history of confusion, retraction and division.

People born here have been thrown out. People not born here have been allowed stay, despite deportation orders. 

Unnatualized British subjects who arrived before 1987 have successfully defied deportation. 

People who have lived here all their adult lives have been thrown out.

The only consistency has been this: it is for the court to determine the meaning of ³alien², not the Parliament. 

It is a constitutional concept not a legislative one.

In short, it is not for the Abbott government to legislate in a way that gives power to the Minister to determine whether someone is an alien whose citizenship can be cancelled.

The discussion paper belatedly put out by the Government suggests a number of options along those lines. 

Someone born in Australia with naturalized parents who were born overseas could lose their citizenship if convicted of terrorism (or maybe even if the Minister merely deemed they were engaged in terrorism without proof).

These citizens would be vulnerable to loss of citizenship because these people might have access to citizenship of another country.

In other words, the laws of a foreign country will determine how this Australian law will operate.

My guess is that this will not pass constitutional muster.

Such a law could not possibly be ³with respect to aliens² because a person born in Australia with at least one parent a naturalized or born Australian could not possibly be described as an ³alien² even if the person¹s parental heritage might give them a right to citizenship of another country.

Nor could it be a law ³with respect to immigration². A person born in Australia to parents who were resident here could not possibly be called an ³immigrant².

Some judges have suggested that if a person has lived in Australia for a long time with a lot of connections here that they have been absorbed into the Australian community and are beyond the reach of the immigration power even if they have not been naturalized.

Others have argued, on the other hand, that those who commit significant criminal offences have not been absorbed into the community.

But no judge has held that a naturalized Australian could ever be deported back to their home country whether they have citizenship, or a right to citizenship, of that country.

And no judge has ever held that a person born in Australia of parents who were here legally but whose parents or grandparents give that person a right to citizenship elsewhere could ever be deported.

Abbott is on new ground here. He is creating two classes of Australian citizen: those born here of Australian parents on one hand and, on the other hand, those either not born here but naturalized or who were born here but have citizenship rights elsewhere.

It is highly likely that the High Court would say the latter group of people are beyond the reach of both the immigration and naturalization power.

Further, the ³naturalization² power would most likely be interpreted as a power to determine the conditions upon which a person can be naturalized as a citizen, but does not extend to a power to ³unnaturalize² them.

Any idea that the Government can take away the citizenship of anyone who has gone through a citizenship ceremony to become an Australian citizen is very likely beyond constitutional power.

The critical point is that the meaning of words ³immigration² and ³alien² in the Constitution is for the court to determine, not for the Government or

the Parliament.

A law that attempts to preclude the re-entry of a person born in Australia or who has undergone naturalization is not a law with respect to ³immigration².

In any event, any law which purports to give the Minister the power to interpret who is an immigrant or who is an alien is certainly beyond the power of the Parliament.

The constitutional principles are similar to those in the Communist Party case in the 1950s. (And so are the political principles ­ a government

preying on paranoia for political advantage.)

Just as Abbott wants to give the Minister power to declare someone a non-citizen without any access to the courts, the Communist Party Dissolution Act gave the Minister the power to declare an organisation Communist or individuals members of the Communist Party and therefore a threat to Australia. It was held to be beyond the defence power.

The thinking here is badly twisted.

If you are going to make terrorism the trigger for citizenship forfeiture, why stop there. Why not pedophiles? Rapists? Murderers?

In any event, loss of citizenship is not going to deter people hell bent on terrorist acts.

But in this week of the 800th anniversary of Magna Carta, the illiberal legal shabbiness of the whole idea is the most dispiriting thing.

For centuries we have reined in executive power by imposing judicial oversight.

It is called the rule of law.

To replace this with a ministerial fiat to deprive Australians of a fundamental right (their citizenship) bespeaks a dangerous authoritarian mindset. And yet another reason for supporting a Bill of Rights in the Australian Constitution.