Just a few weeks ago, Sydney man Chan Han Choi was arrested by the federal police in Australia for selling classified information. He was apparently charged with offences relating to selling information that might facilitate the proliferation of weapons of mass destruction.

Media reports suggested this was very good work by the Australian Federal Police, a point well made by the Prime Minister.

In addition to praising the AFP on their good work, the Prime Minister also took credit for their resourcing and overall performance. In my view, this is a dangerous step too far -- and one of many examples in recent years where senior politicians, who should know better, have tried to leverage police forces or the courts for their political gain.

Read more from JK: Are you living in fear of crime? Read on

The Prime Minister also suggested last year, during question time in the House of Representatives, that he had advice that the High Court would subsequently rule Barnaby Joyce was not a duel citizen of Australia and New Zealand. It, of course, did not ‘so rule’. But again, the Prime Minister got involved with the legal system.

For many, this is almost certainly a small thing, and some don't see it as an issue at all. Some even believe his behaviour entirely justified, if not appropriate. I don't. I view it as a big issue and entirely inappropriate of the Prime Minister.

Malcolm Turnbull is not the sole offender, either. Bill Shorten and the ALP have also made comments about the police and courts. And in the US, President Donald Trump has made any number of divisive, critical and downright disgraceful comments about the judiciary, in particular. Trump is the worst of all.

While it is not well understood by most in the community, or indeed many politicians, I am a big fan of the separation of powers -- and in doing everything possible, and I mean everything, to protect this fundamental tenant of the Westminster system of government.

The separation of powers -- which  is not the same in the United States, because it does not have a Westminster system of government -- involves power in government existing in three independent silos: the legislature, the executive and the judiciary. Under this system, these three silos are not only independent, but they should not interfere with or influence each other. Rather, they should monitor each other and keep each other honest.

It is a protection against corruption.

The legislature in Australia’s case comprises the House of Representatives and the Senate. The executive in Australia comprises the Prime Minister and the Cabinet, with the input of the Governor-General as required. The judiciary comprises all arms of the police and all courts in the legal system. That these three silos are watching over each other to keep each other honest is central to the success of our democracy.

In my view, this tenant of the Westminster system is so important it should be sacrosanct. There should be absolutely no grey areas. This tenant of the system is so important that all political parties and politicians should be expected by us, the community, to never cross any lines. While politicians can praise the police for their good work, and the judiciary for their hard work, it should never go any further than this.

Politicians should never lecture the police or courts, as several have done (including Health Minister Greg Hunt last year). They should never criticise judgments, offer gratuitous advice, take credit for their success, or predict how they will act or rule.

Not only is it essential that governments and oppositions not influence the police or judiciary, it is equally important that they are not seen to try. It is critically important that politicians never do anything to diminish absolute confidence in the police or judiciary, except under extreme circumstances of corruption or malpractice.

I also support development of a federal crime and corruption commission, to which all concerns about the behaviour of people within any of these three silos can be referred.

To work well, there also needs to be a genuine bipartisan, common multi-party agreement on these issues.

What say you?