Mohammed bin Salman, Saudi Arabia’s crown prince. (Will Oliver/Bloomberg)

SAUDI CROWN Prince Mohammed bin Salman is on a mission to charm the West. The 32-year-old de facto leader of one of the world’s largest oil producers paid a visit to Britain last week and is due in the United States next week. His supporters tout him as a bold modernizer who is moderating the severe Saudi version of Islam, granting greater freedoms to women and introducing desperately needed economic reforms. While other Arab states lean toward Russia, the crown prince appears eager to double down on Saudi bonds with the West.

All that is true to an extent, and welcome. Saudi women will finally be allowed to drive in June, and guardianship rules controlling them have been loosened. Religious police have been reined in, and cinemas are opening. The problem is that the liberalizing steps have been accompanied by even bolder acts of repression. Hundreds of Saudi businessmen and princes were arrested late last year and forced to hand over billions of dollars in assets to Prince Mohammed or the government without due process. According to a report in the New York Times, at least 17 were hospitalized for physical abuse, and one, a major general, died.

Those in the West who support the cause of Saudi modernization, and businesspeople who may wish to invest in it, badly need reassurance. Fortunately, there is a ready way for the crown prince to offer it, even before he arrives in Washington: He can release some of the dozens of political prisoners who were jailed for advocating some of the very reforms he is attempting to advance.

Prime among them is Raif Badawi, a blogger and activist who challenged the religious establishment and advocated women’s rights. He was arrested in 2012 and in 2014 was sentenced to 10 years in prison and 1,000 lashes — 50 of which were cruelly delivered in a public square three years ago. In response to international protests, Saudi officials have hinted that Mr. Badawi could be pardoned, but he remains in prison. Now is the time to free him.

The same goes for members of the Saudi Civil and Political Rights Association, who called for political reforms and the reinterpretation of Islamic law. A court dissolved the group in 2013, and most of its members remain imprisoned. So, too, do Mohammed al-Otaibi and Abdullah al-Attawi, who were sentenced to long prison terms in January for founding a human rights organization, the Union for Human Rights, in 2013.

When The Post’s David Ignatius asked the crown prince last month whether he would release some of the political detainees before his U.S. visit, the prince replied, “If it works, don’t fix it.” But if his modernizing is working, why does he need to imprison peaceful advocates of modernization? He should fix that before he arrives in Washington.