South Australian state MP Patrick Conlon has taken up a three-day-a-week, part-time position with law firm Minter Ellison while continuing to serve as a backbencher. The Labor MP, who will keep his $147,000-a-year base salary, has rejected calls from the opposition to resign from Parliament, insisting that he is not breaking any rules.

Is he?

The rules governing politicians’ secondary employment differ across the states but it’s common for MPs to have other jobs. Some lawyers continuing to practice; other MPs operate family farms or run small businesses. The great Paul Keating piggery scandal illustrated how an MP’s outside financial interests can muddy their public image.

In light of the ongoing Independent Commission Against Corruption investigation into former New South Wales Labor MP Eddie Obeid’s business dealings, the NSW Labor Opposition Leader John Robertson has announced plans to ban Labor MPs from having second jobs.

Meanwhile in Victoria, state MP Geoff Shaw continues to be dogged by an expenses scandal, with accusations that he has used public money to cover the expenses of his hardware business — highlighting the pitfalls for MPs who maintain a business at the same time.

Although generally not prohibited from carrying out private secondary employment, MPs are instead asked to declare them in Pecuniary Interest Registers.

The principle of the disclosure of pecuniary interests by MPs is aimed at addressing any potential conflict of interest between their public and private interests. Members are asked to declare any forms of income, including secondary employment.

MPs are in general banned from taking additional employment, such as being a public servant, Council staffer or judge, from the body that employs them as an MP. MPs are not supposed to benefit from a contract with the public service or hold an office of profit from the Crown, or receive pension from the Crown. Former NSW premier Bob Carr has had his $460,000 a year of state entitlements suspended while he continues to serve in the Senate (those entitlements included running an office).

So, can MPs sit in state and federal Parliaments at the same time? The Commonwealth Electoral Act 1918 provides that a person who is a member of a state parliament can’t be nominated as a Senator or as a member of the House of Representatives. So that’s out.

There is no such specific restriction on members of federal Parliament also serving as local councillors, which was highlighted by the case of the Coalition’s Joanna Gash. Gash successfully ran for the position of Shoalhaven mayor while a federal MP (she still sits in Parliament). She has announced that she will not run for re-election at this year’s federal election.

It’s a different story for state MPs. Last year the NSW government brought in legislation banning members of state Parliament from serving as a councillor. The legislation was dubbed the “Get Clover” law after Sydney Lord Mayor Clover Moore who also served in state Parliament and was the most high-profile member affected. Moore chose to relinquish her seat in state Parliament in order to continue as Lord Mayor.

This legislation brought NSW into line with Victoria, Queensland, WA and SA which all prohibit state MPs from serving as councillors (Tasmania is considering a similar ban; the apple isle has had various councillors and mayors sit in its Parliament).