Today’s massive marches across the country suggest that the national argument about gun control has taken a new turn. The National Rifle Association and its political allies seem to be on the defensive. However, it will be harder for protesters to turn people on the street into effective political changes. Even gun control advocates worry about how effective strong laws against, say, the sale of semiautomatic weapons would be in a country where there are millions of privately owned firearms.

While this is a valid question, there are reasons to think strong gun control laws might have consequences even where they seem ineffective. But laws are not only about enforcement and punishment. They are also about setting the ordinary norms of what people find acceptable and unacceptable in everyday life.

Even laws that look unworkable can sometimes work.

One example of how this can work is anti-smoking laws. Over the past 15 years, countries such as Ireland have introduced general legal bans on smoking in the workplace. This means, for example, smoking was prohibited in pubs in Ireland, where drinking and smoking seemed to go together. On the face of it, this ban seemed unenforceable, as it was unlikely that the police would arrest smokers, and the fine was, in any event, relatively small. Irish people are also not noted for their willingness to obey legal rules that seem nonsensical and inconvenient (jaywalking, for example, is nearly universal). However, the ban worked.

The reason for its effectiveness was not that smokers irrationally feared they would be caught and punished. It was that the law shifted everyone’s default expectations. Previously, the norm had been that people who wanted to smoke in public places could smoke, and those who did not like it would have to accept it. Now, that norm shifted, so that smoking was no longer the default. Nonsmokers who did not like the smell and the increased cancer risk felt empowered to complain. Smokers felt less able to resist. The result was that the ban effectively became self-enforcing.

Pro-gun organizations understand this dynamic.

This plausibly helps explain much of the lobbying activity of the NRA and the laws passed by pro-gun politicians. The last three decades have seen a strong push for states to pass ‘open carry’ laws that allow people to visibly carry firearms. They have also seen a concerted effort to widen the number of places in which people are allowed to have firearms. This can be understood as a massive effort in norm engineering. If many people carry guns around with them as part of their everyday activity, and if there are ever fewer places where people cannot carry guns, then guns will seem to be an ordinary and normal part of everyday life.

This will obviously make it harder to restrict firearms and perhaps partly counter the fact that the percentage of families owning guns is declining in the United States. It is unclear whether President Trump’s suggestion that teachers should be armed was guided by any long-term strategy or was a temporarily attractive proposal. It, too, may be seen as normalizing guns in a context where they had not previously been widely accepted.

This has implications for anti-gun organizations, too.

Anti-gun groups, too, are aware of the dynamics of norms. Much of their activity over the past several weeks has been aimed at delegitimizing organizations such as the NRA, e.g. by putting pressure on businesses to withdraw from NRA affinity deals. Over the medium term, they are likely to increase their efforts to roll back the normalization of guns. In the long run, the norm-setting role of laws may give them hope that clear laws can have significant consequences. It would be hard, for example, for a new semiautomatic weapons ban to stop people from using the many semiautomatic weapons that are already in private hands. However, even when laws are hard to enforce universally, they can shape people’s broad expectations about what is acceptable and what is unacceptable in everyday life. A country where it is considered aberrant to possess near-military grade weapons and where guns were again banned in many public places would likely have very different politics around guns than the country in which pro-gun and anti-gun advocates live today.

[An earlier version of this article was posted on February 23, 2018]