Prime Minister Scott Morrison believes "justice will be served" to a spy-turned-whistleblower who revealed Australia bugged East Timor's cabinet rooms.
Lawyer Bernard Collaery and his client, known only as Witness K, are facing criminal charges of conspiring to communicate secret information.
They are due to front the ACT Magistrates Court on Wednesday.
"He'll always get the support from Australia and the consular services that we provide that every Australian can expect," Mr Morrison told reporters in Canberra.
"But at the same time, we'll also respect the laws of our neighbours and other countries, particularly those in our region.
"It's our intention that these things will be conducted in a way that enables justice to be served."
A demonstration led by independent MP Andrew Wilkie and activist group GetUp will take place outside the courthouse, protesting what they believe to be politically-motivated charges against the pair.
Mr Wilkie, along with Greens senator Nick McKim and Centre Alliance MP Rebekha Sharkie, are calling on Attorney-General Christian Porter to drop the case.
"The government shouldn't be going after the whistleblower and his lawyer, they should be going after those who broke the law by spying on East Timor in 2004," said Mr Wilkie, a former intelligence analyst.
"This is an act of political bastardry. Thankfully, there are some who are brave enough to speak truth to power."
Mr Porter has previously said the Commonwealth Director of Public Prosecutions sought his permission to lay the charges and he gave consent after "very detailed, very thorough advice".
Witness K, a former Australian Secret Intelligence Service agent, was a key witness for East Timor in a case against Australia over allegations Dili's cabinet rooms were bugged during negotiations over a gas and oil treaty in 2004.
The person was supposed to give evidence at the Permanent Court of Arbitration in the Hague but was unable to leave Australia because his passport was seized in 2012.
East Timor dropped the spy case against Australia last year as an act of goodwill before signing a new resources treaty.
