Words such as freedom and security invite abstraction until reality intrudes. There is no denying that an alleged plot to behead a pedestrian on a city street is a threat to security. It is also a threat to freedom, as Prime Minister Tony Abbott observed in Parliament this week, ''the freedom to walk the streets unharmed and to sleep safe in our beds at night''. But there is a delicate balance to preserve in Australia's democracy. Overly zealous police or security agents, given too much power without sufficient oversight, can pose a threat to people's freedom. Ask Mohamed Haneef, the Indian doctor detained in 2007 for almost two weeks without charge, accused of terrorism, vilified by having his visa cancelled on character grounds, only to be found to have been grossly wronged. Suspicion is a potent emotion, but it must be tempered by evidence.

Over centuries, the law has sought to restrain the excesses of authorities, a civic compact that is the product of the long experience of finding the balance between community protection and freedom. Governments should be exceedingly careful before meddling with this balance, for the risks of unintended consequences are tremendous.

The federal government has proposed a suite of legislative changes in the name of national security, which Mr Abbott has conceded will mean ''for some time to come, the delicate balance between freedom and security may have to shift''. The reason, according to the government, is to fill ''pressing gaps'' in the present legislative regime. Given all the reviews and amendments in this area of the law since 2001, that claimed urgency should be put in context. This is a time to be cautious, not cavalier.

The Age believes, as would be expected of a media organisation, that the free flow of information is the best defence against threats to public safety. The community will trust open and transparent police and security agencies, and accept the need, within reason, for secrecy around specific operations. The risk that official powers could be abused is best tempered by oversight. That begins with a full examination in the Parliament of proposed new laws. Oversight is extended by rigorous, and properly onerous, obligations on security agencies to report on their activities, for courts to judge the evidence, and for all to be subjected to the scrutiny of a free media. It is of concern that each of these necessary checks could be curtailed by the rush to adopt the present proposals.

A climate of fear does not produce good policy and it is incumbent on political leaders to be measured in their public utterances on national security matters, not stoke an unreasonable panic. The very principles that have held Australia in such good stead - the presumption of innocence and the right to a fair trial - should be defended foremost.

The proposed new laws would see entire regions of the world declared areas where terrorist organisations engage in hostile activity. Any person who travels to such a place would be assumed to be engaged with that terrorist organisation. This extraordinary reversal of the onus of proof - where a person must prove their innocence rather than authorities prove their guilt - should be rejected. How would such a law have applied in Northern Ireland, for example, during the years of the Troubles? Will refugees who flee the brutality of Islamic State in Syria and Iraq be automatically under suspicion?

This kind of draconian measure is not in the long-term interests of Australian democracy. Without doubt, there are people who would do our society harm. But protecting our community also means defending the very freedoms Australians rightly cherish.