When the federal election was called some 1.4 million Australians were missing from the electoral roll.
This erodes the legitimacy of the election argues UNSW professor of law George Williams.
"In a nation that takes prides in its democratic system, this figure is a national disgrace ... it makes a mockery of the idea of compulsory attendance at the ballot box," says Williams, writing in the Sydney Morning Herald.
This "epidemic" of under-enrolment exists despite the best efforts of the Australian Electoral Commission, whose advice to Parliament has been ignored, he says.
Under the current system, enrolment on the electoral roll is not automatic and there is no provision for online enrolment.
"Our political leaders have failed to keep the process of electoral enrolment up with the times. A full system of online enrolment should be a priority for Australia's new government after the election," Professor Williams says.