Mr Skehill will advise members of the Legislative Assembly on ethical issues such as conflicts of interests and the use of their entitlements.

Mr Skehill had a long career in the Commonwealth public service, as Australian Government Solicitor and secretary of the Attorney-General's Department.

In recent years he had been in private practice with Australian-based international law firm Mallesons.

As the Assembly's Ethics and Integrity Adviser, he said the challenge would be applying the members' code of conduct in a variety of different personal situations.

''The real question in these issues boils down to how you apply a highly principled rule in the circumstances of particular cases,'' he said.

''What is a conflict of interest? What may be perceived as a conflict of interest? They're very much judgmental calls and they often require a great deal of analysis.''

Mr Skehill will initially serve for four months until the ACT elections in October.

The appointment will be reconsidered by the next Assembly after the poll.