After decades of discrimination, women in Saudi Arabia are finally going to be allowed into the driving seat. The announcement of a royal decree to this effect from the Saudi Arabian King, Salman bin Abdulaziz Al Saud, is of course good news and a tribute to the tireless campaigning of some notably brave women in the country.

It was always an astonishingly blatant piece of gender discrimination that prevented women from driving in the kingdom. That they couldn't do so without fear of arrest and imprisonment (or even of being sentenced to be lashed) was, in our car-fixated world, extreme even by the standards of the world's more authoritarian countries.

But let's be clear it's a litre or so of fuel being allowed into a bone-dry petrol tank. Women in Saudi Arabia are still very much treated as second-class citizens. It's great they'll be able to drive a car, but whether a driver or a passenger, Saudi Arabian women's lives will still be heavily circumscribed. Diving a car won't change their inferior rights to men in relation to international travel, marriage, divorce, child custody or inheritance.

Moreover, we still need to see how this is going to actually pan out. King Salman's decree announced the setting up of a committee – featuring officials from the Ministries of Interior, Finance, Labour and Social Development – to look into the implementation. The decree won't enter into force before 23 June 2018 anyway, and its text states it will be implemented according to "established legal regulations", without providing further clarification.

What does it mean? Will all women be able to get a driving licence? Will women need to be chaperoned by men in their cars? Will they be the subject of special rules or aggressive attention from traffic police or members of the country's Committee for the Promotion of Virtue and the Prevention of Vice, its so-called "religious police"? We just don't know.

Meanwhile, totemic though the driving ban is in, it's just one part of a very wide set of systemic human rights violations afflicting people in Saudi Arabia.

Remember, this is still a country that bans all political parties, trade unions and protests. A country where peaceful bloggers like Raif Badawi can be sentenced to ten years in jail and 1,000 lashes. A country where scores of people are put to death in bloody beheading executions every year, often after deeply unfair trials. The ugly truth behind the upbeat news this week is that neither men or women are even close to having their human rights fully respected in Saudi Arabia.

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Saudi women will now be able to drive after a decade-long ban was lifted MARWAN NAAMANI/AFP/Getty Images

And this is where world leaders like Theresa May could do more. In merely remarking – as "a longstanding friend of Saudi Arabia" – that this is an "important step" for gender equality in Saudi Arabia, Mrs May barely gets into first gear. The UK has a long and worrisome record of pulling its punches on Saudi Arabia's atrocious human rights record, and some stronger messaging about the country's ongoing round-ups of peaceful critics and human rights activists wouldn't have gone amiss here.

And the timing and manner of King Salman's decree also deserves a mention. The decree was announced at the United Nations General Assembly in New York by the country's ambassador to the United States, Prince Khalid bin Salman bin Abdulaziz.

We cannot be sure, but we fear it may have the effect of dampening enthusiasm for an important UN resolution on the need for an independent international inquiry into the war in Yemen, a conflict that has seen the Saudi Arabia-led coalition repeatedly accused of war crimes.

Brave women rights campaigners in Saudi Arabia have rightly celebrated this week. This was their victory. But there's still a very long way to go yet on this "reform" road in Saudi Arabia. In fact, we've hardly got the car out of the garage yet.

Kerry Moscogiuri is Amnesty International UK's campaigns director.