A federal judge has blocked enforcement of key parts of Idaho's new law that would have criminalised transgender people for using public bathrooms that do not match their sex assigned at birth, finding the measure is likely unconstitutional. US District Judge Amanda K Brailsford issued a 30-page ruling on 16 June, granting a preliminary injunction just days before the law was due to take effect on 1 July.

The relief this brings is real and immediate. Six transgender Idaho residents, represented by the ACLU, the ACLU of Idaho, and Lambda Legal, brought this case. Six people who simply wanted to be able to use a public toilet without fear of arrest. That is the human reality behind the legal language, and it is worth keeping that in mind as we go through what the ruling actually says.

What was the law and what did it do?

House Bill 752 was signed by Republican governor Brad Little earlier this year. It made it illegal to knowingly enter a restroom or changing room designated for the "opposite biological sex" in government-owned buildings and places of public accommodation, including private businesses open to the public. A first violation carried up to one year in jail. A second could be prosecuted as a felony carrying up to five years in prison. Five years in prison, for using a toilet.

Lambda Legal counsel Kell Olson put it simply: "This ruling will allow transgender people throughout Idaho to find and use a public restroom, without the fear of arrest looming over them, while we continue the longer fight to permanently defeat this discriminatory law in court." ACLU lawyer Barbara Schwabauer was equally clear: "No one should be forced to choose between the threat of arrest for being themselves in public or the threat of harassment and violence for acting the way the state wants them to be."

Those two sentences together capture the impossible position this law placed people in. Comply and risk violence, or do not comply and risk arrest. That is not a policy, that is a trap.

Why the judge found the law too vague to enforce

Judge Brailsford found the law likely violates due process because its enforcement standards are so unclear they invite arbitrary and discriminatory application. Her words are worth quoting directly: "Different officers could reasonably reach different conclusions regarding identical conduct, not because the facts differ, but because the statute furnishes no standards by which those facts are to be evaluated."

This is the question these laws never manage to answer: how, exactly, would enforcement work? During oral argument, the state's own lawyers suggested police could use DNA testing to establish biological sex. The judge noted, with what I can only imagine was considerable restraint, that police cannot generally collect DNA without consent, a warrant, or other legal authority. So the state's proposed enforcement mechanism is not only invasive beyond any reasonable measure, it is also illegal.

Brailsford also provisionally certified a statewide class of transgender Idaho residents, extending the protection beyond the six named plaintiffs to trans people across the state. This is not just relief for six individuals, it is a statewide pause on a law that would have affected every trans person in Idaho.

What the ruling does and does not cover

The picture is not entirely clean. Idaho attorney general Raul Labrador has said he plans to appeal, arguing that "biological sex is not vague, and neither is this law." He also noted the ruling was narrow: parts of the law relating to locker rooms, showers, and changing rooms remain in effect. The ruling allows trans people to use single-stall toilets matching their gender identity, or multi-cubicle bathrooms when a single-stall is unavailable, but the state may continue to enforce the law for multiple-user bathrooms and public locker rooms or showers.

So this is a partial, provisional victory, not a final one. The fight continues. But the fact that a federal judge looked at this law and found it likely unconstitutional before it even came into force is significant. Courts keep arriving at the same conclusion: you cannot legislate against a group of people's existence in public space without being able to explain how you would enforce that, and against whom, and on what evidence.

What I keep coming back to

Every time I read about these laws, I think about what it would feel like to live under one. To get up in the morning and wonder whether using a public toilet today might result in your arrest. To have to plan your route through the world around which spaces might get you reported, questioned, or charged. Trans people in Idaho were facing exactly that from 1 July, and six of them decided to fight it. I am glad they did, and I am glad the court listened.

The attorney general will appeal. The law is not dead. But for now, trans people in Idaho can use a public toilet without the threat of a felony charge hanging over them, and that is genuinely good news.

If there is a news story you would like me to cover then just let Sammy know.

Dr Helen Webberley is a gender specialist, medical educator, and founder of GenderGP. She writes about gender diversity, trans healthcare, and the lives of trans people and their families.