Much has been written about these new laws in a short space of time; and most of the views have opposed providing agencies with new powers. Tellingly, such analysis and commentary rarely suggests viable alternatives for how authorities can be empowered to stop foreign fighters from travelling.

In some instances, criticism of the laws has been very misleading. These laws will not criminalise travel, as some say. They will, however, make it easier to prosecute those who travel to defined conflict zones for illegitimate reasons. This law might save lives.

Customs officers are not being given the power to detain people without charge. But the new legislation does lower the threshold at which a person can be questioned by Customs, and extend the period before the person is allowed to inform someone that they are being questioned.

The new provisions will provide Customs officers with time to find more out about a traveller, and to prevent that person from communicating with an accomplice for two hours.

That intervention by Customs may be enough to create doubt in another conspirator's mind about the 'trustworthiness' of the person being questioned. It might be enough to stop a tragic chain of events that leads a person from Australia to Iraq's desert towns.

This change is one among many that go to the heart of disruption tactics.

The Act will also give law enforcement agencies new powers in terrorism cases. In all cases, these laws require the community to have a high degree of trust in the agencies, particularly those concerning delayed notification warrants and foreign evidence.

Both powers give police significant advantages over suspected terrorists at the cost of some existing freedoms. Safeguards are essential.

Delayed notification warrants allow police to gather evidence from unsuspecting suspects in terrorist cases. And police are now empowered to enter through adjoining properties. There are prohibitions upon reporting such activity. This power is intrusive.

Also, police will also be able to introduce more types of evidence into court in cases where Australians have involved themselves in overseas conflicts. In the past, police have been frustrated by the difficulty with having to work through unco-operative, incompetent or absent governments in this type of case.

But the old situation gave criminal fighters a relatively free hand to go to a warzone and contribute to others' misery. This new legislation will increase the options for police to gather evidence against these people and use it.

The safeguards around these powers have included new review clauses, a greater role for Parliament and the Independent National Security Legislation Monitor, specific directions for judges, and judicial approval for the delayed notification warrants. In the case of these warrants, there's also a requirement for the Commonwealth Ombudsman to be informed of their use.

There is also an increased level of accountability placed upon the agency heads - including the Director General of Security and Commissioner of the Australian Federal Police - to ensure these powers are used appropriately.

This kind of oversight needs to be both formally enforced, and also supervised by the sometimes unstated oversight mechanism: ministerial responsibility. Ministers should use the full extent of their authority if they ever suspect that agencies have misused their powers, and, where they are part of formal approvals, exercise these with diligence.

While these laws are necessary, they are not sufficient.

There's a real question about what the Australian government will do with people who've had their passports cancelled or suspended. It's impossible - and undesirable - to put them all under surveillance.

The Australian government should advance its work on programs to dissuade or de-radicalise those who intend to participate in violent jihad, especially those who know their passports have been revoked. This may take almost bespoke solutions, and active involvement from relevant communities, due to the diversity of the people involved.

While this sounds challenging and resource-intensive, such programs would be positive additions to the powers that have been provided under this new legislation.

David Connery and Clare Murphy are with the Australian Strategic Policy Institute in Canberra