OPINION: Stephen Gageler's appointment as Australia's next High Court judge reflects his legal ability and the broader policy objectives of the Commonwealth. Much has been made of the former, without recognition that the latter provides a key subtext.

After suffering several major losses, the Commonwealth hopes that his and further appointments will shift the court in its favour.

As a brilliant constitutional lawyer and a decent and generous person, Gageler will make a very fine High Court judge. It has long been a matter of when he would be appointed, rather than if. His expertise is particularly desirable now given that he replaces Justice William Gummow, long the court's foremost constitutional lawyer.

All this enabled the Attorney-General, Nicola Roxon, to announce Gageler as the ''best person for the job''. However, as Gageler himself has said, it is ''naive'' to suggest that such appointments are based only on merit. Other factors are always in play.

The Commonwealth has a monopoly on selecting High Court judges, and not surprisingly promotes its own interests. As a result, it is unusual for the High Court to have even a single judge who has professed sympathy for states' rights.

Instead, the High Court has been dominated by judges from the larger states. Of 49 appointments, 39 have come from NSW and Victoria alone. No judge has hailed from South Australia or Tasmania. Neither state has ever produced the ''best person for the job''.

Current appointments reflect unusually high Commonwealth concern about the direction of the High Court. The greatest anxiety arises from decisions on the federal power of expenditure.

Spending taxpayers' money is crucial to how the Commonwealth dictates policy and action across the nation. Very often, it gets its way not by making new laws, but by applying its vast financial capacity to create incentives and fund new projects.

The Commonwealth's assumption that it could spend money on whatever it wished was demolished by the High Court in the Pape case of 2009. Rather than backtracking, the High Court installed even more stringent limits on federal power in the school chaplains case in June this year.

These two decisions have rung alarm bells throughout the federal government and its departments. The latest case prompted an emergency rescue package, not only for the school chaplaincy program, but also for up to 10 per cent of all federal government expenditure.

More pain may be on the way. Ron Williams, who brought the chaplaincy case, is launching another challenge directed at the rescue package. Despite the complications and inefficiencies brought about by this outcome, there is a good chance he will succeed. The Sydney University professor Anne Twomey has gone so far as to predict that the Commonwealth is facing ''another clobbering by the court''.

The Commonwealth will no doubt hope its losses can be mitigated, or even reversed. It certainly has time on its side. Four of the seven High Court judges will retire over the next three years. The Gillard government will make one further appointment in the coming months, with two more judges then to be replaced in 2015.

On this issue, Julia Gillard and Tony Abbott will likely be in sync. Both will want the High Court to allow the Commonwealth to spend money as it wishes.

With such considerations in play, it is easy to see why the government regards Gageler as the ''best person for the job''. Australia has never before had a High Court judge with such extensive federal experience.

Although he hails from country NSW, Gageler completed his law degree at the Australian National University in Canberra and spent early years as a lawyer in the federal Attorney-General's Department. After practising at the private bar in Sydney, he returned as Solicitor-General in 2008.

With this background, Gageler brings a unique sensitivity to and understanding of the workings of the Commonwealth. He can serve on the High Court until 2028, and the Gillard and future governments will hope that he leads the charge in support of a broader reading of federal power.

Whether things work out this way remains to be seen. Gageler has no prior judicial record, and his writings on constitutional law provide only hints and suggestions as to how he might decide cases.

He will also apply the independence and deep thinking required of a High Court judge. This may mean that he surprises his appointers.

George Williams is a Professor of Law at UNSW. 

This opinion piece first appeared in The Sydney Morning Herald.