As part of his role as an energy consultant, Simon Holmes a Court uses social media to discuss energy policies across the political spectrum.

But that's not always possible, he says, because some elected representatives have blocked him, including Liberal Democrats Senator David Leyonhjelm, Liberal Senator Eric Abetz and Victorian Opposition Leader Matthew Guy.

"Social media is about communication. It's really no different to calling up their electorate office and being hung up on, or writing a letter and having no one reply," he says.

Social media has become a vital tool for many politicians, not just to update followers on their work but to actively engage in political debate.

And people do respond — from retweets and hyper-partisan support to challenges on policy and outright insults.

Social media has breathed new life into the stagnated relationship between elected official and voter — but that relationship gets cut off if a politician blocks accounts.

To block or not to block?

Professor Katharine Gelber from the University of Queensland says social media is a key communication tool and that politicians "shouldn't be allowed to block someone just because they disagree or because they're criticising you".

"What we're seeing in Australian politics right now is a decreasing awareness on the part of politicians that democracy requires robust criticism and that people have the right to engage in very robust criticism of government," she says.

"Government needs to have a thick skin and wear it, because that's how democracy works and instead what we're seeing is politicians not liking what someone is saying and blocking them."

Trump could be banned from blocking

In the US, this issue is about to hit the courts again and it could radically change how US politicians — including President Donald Trump, whose fondness for Twitter is legendary — run their social media accounts.

Trump's habit of blocking those who disagree with him has already been slapped down by a court in New York. In 2017, several Twitter uses argued that Trump had unconstitutionally suppressed their voices, and they won, but it is being appealed by the Justice Department.

A former CIA agent started this GoFundMe to buy Twitter and ban Trump. ( GoFundMe: BuyTwitter )

In a separate case, a constituent is taking Virginia's Loudoun County Board of Supervisors to court after he was banned from one of the supervisor's Facebook pages, claiming it violates the first amendment.

If Brian Davison wins, it will set a precedent that will effectively make it unconstitutional for government officials, including Trump, to block or delete comments on their official accounts just because they don't agree with them.

The case is about disagreement — blocking someone because their opinion is different or because it challenges the government official's stance. It does not refer to trolling, abuse or spamming, which Professor Gelber says should be the only reasons for politicians to block accounts.

In Canada, a growing number of complaints are being made of politicians and government officials blocking users — almost 22,000 users across Facebook and Twitter, and 1500 posts have been blocked and deleted in recent years.

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Australia's biggest blockers

In Australia, blocking and deleting is a practice that has not gone unnoticed by social media users.

I asked people on Twitter to disclose which politicians had blocked them and I was flooded with responses.

There were a handful of names that came up repeatedly and many of them are politicians who often speak loudly about freedom of speech: Liberal Democrats Senator David Leyonhjelm, One Nation Senator Pauline Hanson and Nationals MP George Christensen.

Former Foreign Affairs Minister Julie Bishop was also mentioned, as was Tasmanian Liberal Senator Eric Abetz and Prime Minister Scott Morrison.

Julie Bishop was mentioned by Twitter users as a frequent blocker. ( ABC News: Nick Haggarty )

Professor Gelber says it's ironic that the politicians who laud freedom of speech are also apparently some of the quickest to complain when someone says something they don't like.

The list was not exclusive to conservative politicians, though, with Greens Senator Sarah Hanson-Young and Senator Derryn Hinch also mentioned for their blocking.

Many users claimed that they had been blocked after they challenged a politician's stance or policy, or expressed a different point of view.

Senator David Leyonhjelm of the Liberal Democrats party. ( Supplied: baronsp.com )

Freedom of speech not a right

Senator Leyonhjelm said he had only blocked accounts that had been abusive, not because he disagreed with them.

"I'm pretty reluctant to block anyone … it has to be because of personal abuse and it has to be quite obnoxious," he said, although he admitted that he has muted several users who disagreed with him, but only because they "filled up my Twitter feed".

When asked if he would support any moves to ensure that politicians could not block constituents on social media, Senator Leyonhjelm said no, citing the difficulty of enforcing such a rule.

Professor Gelber says that unlike America, Australia has not enshrined freedom of speech in law, and especially not the constitution, so challenges like the ones occurring overseas couldn't be mounted in the same way.

"We need a Bill of Rights, although I don't think that will happen anytime soon. But we do need protection of free speech, and restrictions where it's appropriate, but more robust protection than what we have now."