Canada appears to be preparing to do as Australia has long done: making a record of anyone's and everyone's departure from the country – including its own citizens.

Entering or leaving a country, crossing an international boundary, is hardly a private act. Any border is an expression of at least one nation-state. Crossing it is not like phoning a friend or sending an e-mail. Consequently, it does not give rise to a reasonable expectation of privacy – a concept that is central to the discussion of interception of communications and other debates about privacy.

The sharing of entry and exit data between Canada and the United States is in the works, according to a number of media reports. This is an extension of previous phases of co-operation between the Canada Border Services Agency and the Department of Homeland Security.

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It is true that all this is easier to achieve for Australia, which has no land borders, and where most departures involve getting on an airplane. But in Canada, similarly, all airplane passengers are already providing basic information about themselves to an airline corporation.

The government's plan is that RCMP and CSIS would have access to this information on a "need-to-know" basis.

The CBSA wrote last summer to Steven Blaney, the newly appointed Minister of Public Safety, pointing out the participation of Canadians in terrorism in foreign countries. For example, two young men from London, Ont., took an active part in the murderous assault on an Algerian gas plant a year ago. CSIS had been observing the members of this group before any of them left Canada, but the Canadian authorities were unable to take any notice of their departure. Exit records, if they had been available, might have helped.

Such records may also assist in verifying the fulfilment of residency requirements for citizenship applicants and permanent residents. And the Canada Revenue Agency could be interested in verifying the accuracy of Canadians' assertions about where they are living for most of a given year.

There must be scrupulous limits to access to such exit data. But the creation of departure records is not in itself a violation of the principles of privacy.