A new poll suggests a majority of Canadians approve of the Liberals' plan to legalize marijuana but have mixed views about some provisions, as well as doubts that it will succeed in cutting organized crime out of the trade and keeping marijuana out of the hands of underage users.

The survey, conducted by the Angus Reid Institute (ARI) shortly after the government tabled its marijuana legalization legislation last week, found that 63 per cent of respondents were strongly or moderately in favour of the Liberals' plan. Just 37 per cent were opposed.

A majority of Canadians of every age were in favour of the legislation, though support was strongest among those 18 to 34 years old (72 per cent).

The poll also found that 58 per cent of Canadians polled thought that marijuana legalization would do more good than harm, whereas 42 per cent felt that it would do more harm than good.

But on some of the specific provisions in the legislation, ARI found that Canadians' views were less clearcut.

Though 45 per cent of Canadians felt the limit of 30 grams for personal possession was "about right," 26 per cent felt that it was too much and another 22 per cent felt that no amount should be legalized.

Just seven per cent thought that the personal limit should be higher.

The split was similar on allowing Canadians to grow four marijuana plants within their own homes: 43 per cent thought the limit was about right, 11 per cent thought it was too low, 18 per cent thought it was too high and 29 per cent believed that Canadians should not be able to grow marijuana in their own homes at all.

Taken together, the results suggest that some 52 to 54 per cent of Canadians agree with the Liberals' proposal or feel the laws should be even more permissive, while 47 to 48 per cent express some reservations with the plan when the details are laid out.

Pot at 18 too young

This discomfort was especially high concerning the legal age for buying marijuana, which the federal government will set at 18 (provinces will be free to set it higher). Fully 58 per cent thought that the legal age should be higher than 18, while 42 per cent felt that the government was on the right track.

Even among supporters of the government's legislation, more than two-in-five disagreed with setting the legal age at 18.

This echoes a recent Ipsos poll conducted for Global News before the legislation was tabled. It found that 49 per cent of Canadians thought 21 was the right legal age for buying marijuana. Just 23 per cent thought 18 was the right age. Another 23 per cent chose an age between 18 and 21, while five per cent felt the age should be set at 16 or 17.

Doubts that preventive measures will work

The Liberals have presented their plan to legalize marijuana as one that will help keep pot away from kids and the marijuana trade out of the hands of organized crime. According to the ARI poll, Canadians have doubts that will happen.

Fully two-thirds of respondents believed that measures to discourage marijuana use would fail to prevent underage users from consuming even more marijuana when it is legalized. A slim majority, or 55 per cent, believed that organized crime would still find a way to profit from the trade.

But some concerns raised about increased use of marijuana seem misplaced. The Ipsos poll found that just 26 per cent of Canadians said they would be more likely to use marijuana after its legalization — and these were primarily people who were already habitual users.

Among those who have never smoked pot, just 6 per cent said that legalization would make them more likely to give it a try.

The poll by the Angus Reid Institute was conducted between April 17 and 19, 2017, interviewing 1,467 Canadian adults who were members of an online panel. A probabilistic sample of this size would yield a margin of error of +/- 2.5 percentage points, 19 times out of 20.

The poll by Ipsos was conducted for Global News between April 10 and 11, 2017, interviewing 1,004 Canadian adults who were members of an online panel. A probabilistic sample of this size would yield a margin of error of +/- 3.1 percentage points, 19 times out of 20.