Residents in California are welcoming new laws of legalising the recreational use of marijuana this morning.

California is now one of six American states to legalise recreational marijuana use , which means people aged 21 and over no longer require a medical license to purchase and use the drug.

The new law is sparking discussions in Australia on whether we should do the same and what dangers may be involved.

Should recreational marijuana use be legalised in Australia? Yes 25045 No 1661

Marijuana advocate Greg Barns said it was inevitable that the laws would eventually change in Australia to make the drug legal.

“There is a global trend now, not just in California, but you will see on July 1 this year, the whole of Canada moving to legalise the personal use of cannabis,” Mr Barns said.

“Australia will come to it and we ought to come to it. We ought not criminalise what is a legitimate activity on people utilising this drug.”

However, Drug Free Australia executive officer Jo Baxter said she hopes the drug will remain illegal in Australia.

A customer's cannabis items purchase at the Harborside cannabis dispensary in Oakland, California. (AAP)

“It’s actually quite a harmful drug and if we think we make it more available, that’s the way to do it,” she said.

“I think it’s harking back very closely to the big tobacco move in the 50s where tobacco was sold as something that was safe and good for the nerves and would calm you down.

“Now that myth pervades the cannabis industry which really is not true. It is a gateway drug.”

An ecstatic customer after making a purchase and wearing his free t-shirt at the Harborside cannabis dispensary in Oakland, California. (AAP)

Ms Baxter said the biggest harms related to legalising the drug included increased use, crime figures and health issues.

“When something is legalised, you get the sense that it’s okay to do it so it will increase use and that’s been proven in Colorado for example,” Ms Baxter said.

“There’s also a burden on our public health system because when people get lung diseases or mental health issues they go in for treatment.”

The question is whether the recreational use of marijuana will be legalised in Australia.

Mr Barns said crimes rates in the US had decreased since the drug was legalised in the five other states as people no longer had to resort to illegal means to obtain the drug.

“If you can buy the drug in a legal dispensary, you no longer need to pay the premium price and you no longer get into debt with drug dealers,” he said.

“It's a regulated market. We should recognise reality. Young kids are taking and using cannabis. We ought to make it from the age of 18 in Australia.