FOUR years ago this week the whistle-blowing accountant Sergei Magnitsky died in jail from beatings and abuse, having uncovered a $230m fraud against the Russian state. His client Bill Browder, a London-based financier, has been campaigning to punish those responsible with visa bans and asset freezes. But the Russian authorities have retaliated and are trying to extradite him on fraud charges, using Interpol, the world police co-operation body.

No Western country is likely to send Mr Browder to Moscow. But his travel plans are stymied by the risk of arrest . He had to cancel a visit to Sweden last month to talk to a parliamentary committee. Only after weeks of lobbying did the country’s police remove Mr Browder from their database. Germany, France and Britain have also publicly snubbed Russia’s request.

Interpol notes that its constitution prohibits “activities of a political, military, religious or racial character”; governments are not supposed to use it to settle scores with their opponents. Nevertheless its “Red Notices”, which seek the discovery and arrest of wanted persons for extradition, are open to abuse. Once issued, a Red Notice encourages—though it does not oblige—190 countries to detain the person named. 8,136 were given out last year, an increase of 160% since 2008. Interpol insists that it is not a judicial body: “queries” concerning allegations are “a matter for the relevant national authorities to address”.

But Mr Browder’s case is just one of many arousing controversy. Three years ago Algeria issued a Red Notice against Henk Tepper, a Canadian potato farmer, in a row involving export paperwork and suspect spuds. He was released in March after a year in a Lebanese jail and wants to sue the Canadian government for not protecting his rights. Interpol took 18 months to accept that the Red Notice issued against Patricia Poleo, a Venezuelan investigative journalist, by her government was politically motivated. Indonesia pursued Benny Wenda, a West Papuan tribal leader who ended up marooned in Britain; Belarus hounded an opposition leader, Ales Michalevic, when he fled to Poland.

Russia seems particularly fond of the tactic. It has targeted political refugees, such as Petr Silaev, an environmental protester, and Anastasia Rybachenko, a student activist now stranded in Estonia. She says Interpol is being used to “undermine democracy”. During recent elections in Estonia, Russia also reissued a Red Notice for Eerik-Niiles Kross, a politician and former spymaster who has long been a Kremlin bugbear.

Fair Trials International, a campaigning group, wants Interpol to have greater powers to vet “abusive, incomplete or inaccurate” arrest requests before they are sent to police forces around the globe. Though all Red Notices are issued to law-enforcement agencies, fewer than half are then made public. That makes it hard to challenge them in advance, or to prepare a defence in the event of a surprise arrest at a foreign airport. Fair Trials also wants an independent body to hear appeals instead of the Commission for the Control of Interpol’s Files, which it says is too secretive.

Billy Hawkes, the commission’s chairman, says its decisions in individual cases are formally only recommendations to Interpol’s General Secretariat. He admits that aspects of its activities are “unsatisfactory”, but argues that for a possible innocent person, having a Red Notice spread over the internet would be worse than issuing it in secret.

Dominic Raab, a British MP, worries that diplomatic expediency is compromising citizens’ rights. Ken-Marti Vaher, Estonia’s interior minister, decries requests of “a dubious nature” made to Interpol, and points out that Russia has failed to accept any of his country’s offers to help investigations concerning Mr Kross. Mark Stephens, a British lawyer, says few governments are protesting about abuse because no one wants to be seen taking the side of criminals. At present, he says, challenging Red Notices is like a “game of battleships”: the defence is shooting in the dark, unaware of the size and scope of the target.