Only some of us are old enough to remember when smoking in restaurants was normal, and going out at night meant smelling of tobacco smoke whether you smoked or not. Seatbelts were optional and more than three kids sat in the back seat (as many as could fit actually). What changed? Legislation.

I have surprised myself that it has taken me this long into my blogging journey to dedicate a blog to my most favourite of public health interventions, legislation.

In my shift from clinical medicine to public health, I remember being fascinated by the power of public health interventions. Intentional shifts in the way society works with sweeping impacts on human behaviour as a result. For example, we are familiar with major interventions such as the suite of tobacco control initiatives or the many different road rules in legislation that collectively make our roads safer.

There is little debate that the major changes we have seen in public health, from sanitation, food safety, control of poisons in our environment or human rights, have been implemented through legislation. These laws have a reach across the state or nation, and in some cases internationally which is near impossible to achieve with other methods.

These laws act on the population to shift behaviour in different ways. The most common is through the use of bans or mandates. Tobacco laws banned smoking in many public places to reduce exposure to second hand smoke, particularly on children. This ban also had the effect of changing the level of acceptability of public smoking, with benefits that went beyond reduction in second hand tobacco to help reduce the number of smokers overall. Laws can also act through incentives or disincentives, such as using a tax to increase the price of a product to the extent that it reduces consumption of the product.  This approach is being used in Mexico, among other countries, to reduce the consumption of soft drinks (sugar sweetened beverages) with good effect.

Laws can also benefit wellbeing by removing bans. The Marriage Act 1961 was amended in 2017 to define marriage as the union of two people, regardless of gender, overturning the ban on same sex marriage. Another example is abortion law, which in Australia has shifted towards more allowance for pregnant people and their health professional to make decisions about abortion, away from the many restrictions that had been placed in law for abortion care.

A major benefit of legislation is that the change is sustainable. Laws are not subject to sudden loss of funding or short term projects ending, because they are much harder to change. If they are well designed and also are able to be well enforced, it is likely that changes they bring about will be sustained. Over time, these rules become part of our daily lives, barely noticed.

While laws are difficult and slow to change, in general, there is a system that allows this to happen. Parliament and the political system is entirely built around legislation and changing the legislation to meet the needs of the population. This means that change is possible if we understand the way the system and the people within it work.

It is fair to say there are other possible ways to make these kinds of sweeping changes, such as through funding allocation or even, more rarely, mass movements. These examples can often lead to change, but in many cases these changes are realised in the long run through law. Think for example about major funding decisions of government which generally require legislative backing. Or the #MeToo movement which led in many places around the world to changes in workplace law, and limiting non-disclosure agreements which protected perpetrators.

In public health, we should always be thinking about the relevant legislation in the area we work in to question if it best serves the community, how it could be changed for the better or if legislation is required where there isn’t any. These changes are difficult to make, but they endure long past us to benefit the community if they are effective and well enforced.