What does the national school chaplaincy program do?
The role of chaplains is to support the emotional well-being of students in schools. The National School Chaplaincy Association says chaplains are in the "prevention and rescue business" and help young people deal with issues ranging from family breakdown to drug abuse.
The association says school chaplains encourage reflection on the "spiritual dimensions of life" and have an "educative role" in morals, values, ethics and religion. But it stresses that chaplains are available to students of all faiths and are expected to respect the range of views and affiliations in schools.
What did Ron Williams argue?
Under the Australian constitution, Parliament can only directly fund things that are attached to a number of powers, known as "heads of power". These include defence, immigration and foreign affairs. Anything else must be funded by passing legislation sufficiently connected to it, and by granting state governments the money to spend on certain things.
In Mr Williams' first High Court challenge, he successfully argued that Commonwealth direct funding for school chaplains went beyond the Commonwealth's executive powers.
The-then Labor government changed an existing law, giving itself power to fund an open list of about 427 things, including school chaplains. In total they amounted to between 5 and 10 per cent of Commonwealth expenditure. This was passed unanimously in both houses.
In his latest challenge, Mr Williams argued that this law was totally invalid, and that the payment to chaplains was unconstitutional because it was beyond the Commonwealth's powers and had not "validly been authorised by legislation".
What did the High Court decide?
The High Court decided that the law was invalid for the Commonwealth's funding agreement with the Scripture Union of Queensland for school chaplains, because chaplaincy services did not fall under the Commonwealth's power to make laws that provide "benefits to students". Most of the judges said that while the services were aimed at "desirable ends", they could not be defined as "benefits" because they did not provide "material aid to provide for the human wants of students". Justice Susan Crennan said because students could choose to take up the services, the program had no "prescribed" beneficiaries.
The court also decided chaplains did not fall under the corporations power, as was argued by the Scripture Union of Queensland.
How will the High Court's decision affect school chaplains?
Prime Minister Tony Abbott reiterated his support for the national school chaplaincy program within hours of the decision being handed down.
The program could still continue to be funded via conditional grants to state governments.
What other programs will the High Court decision affect?
The High Court only held that the law's attempt to fund the chaplaincy program was invalid. It did not strike down the whole law or any of its other funding arrangements. But it said that the law should be read to only give the Commonwealth power to fund things that fell under one of its constitutional heads of power.
Sydney University constitutional law professor Anne Twomey says that most of the other programs will "probably" be valid, because they fall under one of these powers. But she said the decision left it open for those that were not to be similarly challenged in the High Court.