Labor is still open to considering lowering the voting age to 16 but Special Minister of State Chris Steel said it's difficult to do without undermining the principle of compulsory voting.
Mr Steel said Labor had "deeply considered" lowering the voting age over the past year but the party could not agree with the bill put forward by the ACT Greens.
The Greens' bill to lower the voting age was voted down by the ACT Legislative Assembly on Thursday afternoon during a fiery debate.
The bill would have made it compulsory for 16 and 17 year olds to vote in ACT elections but it would not apply to federal elections.
Greens backbencher Johnathan Davis, who co-sponsored the bill, said Labor's failure to support the bill meant the party had never genuinely considered the bill. He said the bill was introduced in late 2021 and Labor had nearly two years to consider it.
"If ACT Labor were genuinely considering lowering the voting age, if they were actually committed to their own platform, then if they don't like the Greens amendments, they should propose some alternatives," he said.
"The absence of amendments from the Labor Party today suggests that they've wasted our time, the Assembly's time and these young people's time for the last two years on a wild goose chase."
Labor policy platform said the party would consider lowering the voting age but it had concerns it could unfairly penalise younger people.
The Greens had originally supported lowering the age on a voluntary basis but changed this position ahead of introducing the bill.
The original bill from the Greens proposed lowering the fine for not voting from $20 to $10 to make it more accessible for younger people. However, the Greens amended this to say first-time voters would not receive a fine and would receive a warning instead.
Mr Steel said this would undermine compulsory voting. He said while Labor would consider lowering the age there was no model available that would not penalise young people or undermine compulsory voting.
"We always knew that it was going to be very difficult to extend the vote to young people whilst also respecting our compulsory voting system in Australia," he said.
"We're not aware of any way that you could extend the vote to young people without undermining compulsory voting in Australia."
The Liberals voted against the bill with deputy opposition leader Jeremy Hanson saying the bill was an attempt from the Greens to increase their voting base.
Greens backbencher Andrew Braddock, the bill's other co-sponsor, said young people were already subject to other fines. He said the party had added the warning in response to Labor's concerns.
"Young people are regularly subject to fines, whether it be $125 fine for parking, it might be a littering fine for $75," he said.
"We brought forward amendments that instituted what is called a warning for new voters. These are people who have gone on to the roll either as a result of coming of age, or have been newly conferred as an Australian citizen."
