Students will return to voluntary union membership with the Government set to back a historic bill through parliament tonight.



ACT MP Heather Roy will get the backing of all of the National Party MPs when her Education (Freedom of Association) Amendment Bill has its second reading tonight. The bill will not pass in to law until it passes it third and final reading later this year, but the support of National tonight means it will almost certainly succeed.



It is a controversial bill, prompting bitter arguments and nearly 5000 submissions.



It would strip the right for tertiary students' associations to make people join when they enrol at a university or polytechnic.



Currently, membership is compulsory unless students force a referendum and a majority support voluntary membership. Only Auckland University, which first voted in 1999 to become voluntary, does not have compulsory union membership.



Mrs Roy today said she and other MPs had been subject to a "last ditch, dirty tricks" campaign to try and defeat the bill. Critics of the bill had sent a deluge of messages via email, she said.



The bill was returned from the education and science select committee at the end of last month after considering 4837 submissions - 4418 of which were form submissions. The committee also heard 132 oral submissions in Dunedin, Christchurch, and Auckland.



Both the Labour and Green Parties will not support the bill because they say it will destroy the associations.



"And as a result will undermine the educational success and campus experience of many students," Labour said in its minority view on the bill.



The bill is expected to be debated around 7:30pm tonight.