Should developers be able to make political donations? Or anti-abortion advocates protest outside abortion clinics? How much should campaign groups be able to spend on political ads? And can public servants really be sacked for their tweets?

Those aren’t topics for high school debates or questions to be posed on the next episode of Q&A. They are all questions of free speech raised by cases before the high court to be heard or decided in 2019.

With this bumper crop of cases invoking the implied freedom of political communication in the constitution, the court will define the limits of free speech in Australia.

They come at a time when arguments for a human rights charter – long a demand of the left in Australia – have been reinvigorated from a surprising quarter, as human rights discourse is taken up by conservatives in the religious freedom debate.

The cases looming in 2019

The first cab off the rank should be a decision in the Unions NSW challenge against the Berejiklian government’s Electoral Funding Act, which restricts registered third-party campaigners (such as GetUp or unions) to spending $500,000 in the six months before an election.

That case was given an urgent hearing in December, with a decision needed before the 23 March state election.

There shouldn’t be long to wait for the high court’s verdict in parallel challenges against laws establishing safe zones around abortion clinics in Victoria and Tasmania.

Based on the hearing in October the justices seemed persuaded the law has a legitimate purpose to protect safety, privacy and dignity, but Tasmania’s law could be struck down over drafting that bluntly bans protests about abortion rather than focusing on the effect of speech on people accessing abortion services.

In Comcare v Banerji, the high court must decide whether implied freedom of speech can rescue a public servant sacked for sending anonymous tweets critical of the immigration department.

This case could be decided on a technicality. The attorney general has argued the implied freedom determines whether the power to sack a public servant is constitutional, but cannot override a particular exercise of that power.

It’s still early days for the former Liberal National party president Gary Spence’s case seeking to overturn Queensland’s ban on developer donations.

Spence’s submissions in a preliminary hearing made the eyebrow-raising claim that the influence of developer donations on politics is less of a problem in Queensland than in NSW, but there are no detailed submissions or hearing dates in this case yet.

At the end of all that, Australia could have one or two decisions akin to the United States’ supreme court’s 2010 Citizens United ruling – a decision that political ads and donations are vital for democratic debate, unleashing a torrent of new spending on political campaigning.

Or the implied freedom could be limited to striking down laws that are gross abuses of state power, but leaving it up to governments to set rules about when and how campaigning can be conducted.

Outside the courts

The courts are just one arena for free speech questions. Another is public debate about a human rights charter, already decades-old but amping up yet again.

At Labor’s national conference in December, delegates narrowly voted down a proposal from the party’s left faction to establish a charter of human rights.

A charter would entrench in Australian law obligations in the international covenant on civil and political rights to protect the right to life, freedom of religion, freedom of expression, the right to peaceful assembly, freedom of association and the right to non-discrimination and equal protection of the law.

A charter has long been opposed by conservatives, such as John Howard, on the basis it would shift power from democratically elected governments to unelected judges.

It was a thing to be feared or reviled. Who can forget Tony Abbott warning that constitutional recognition of Indigenous Australians should not become a “one-clause bill of rights”?

But Australia’s failure to do more to enact article 18 of the covenant – freedom of religion – has suddenly made rights discourse a conservative cause too.

Free speech and religious freedom are invoked by conservatives for everything from the need to keep “counsellors” outside abortion clinics, to protecting the ability to teach the definition of marriage between a man and woman in schools, to seeking guarantees charities will not lose their charitable status if they contradict the civil definition after the legislation of marriage equality.

That’s why the Morrison government accepted the Ruddock religious freedom review’s recommendation to create a religious discrimination act and also promised to give “equal status in international law of all human rights, including freedom of religion”.

It’s a distance short of what the Human Rights Law Centre wanted – a human rights act to legislate all the covenant’s rights.

But with Australia’s limited protection on free speech getting a workout in the high court and religious freedom set to be one of the final legislative priorities of the Morrison government, it’s a safe prediction that rights discourse will be the rage in 2019.