Oh, the tasks that confront a Russian tsar. You must guide the affairs of a country spread across nine time zones. You must set its policies on the world stage. And then, if you are Vladimir Putin, you must determine the sentence of three members of a female punk rock band who misbehaved in a church. Seemingly trivial stuff, but the decision could shake the foundations of your power.

Today, a Moscow court is due to deliver its verdict (or more exactly Vladimir Putin's verdict) in the case of Nadezhda Tolokonnikova, Yekaterina Samutsevich, and Maria Alyokhina, three members of the Pussy Riot rock group who on February 21 performed a so-called "punk prayer" before the altar of the Cathedral of Christ Saviour in Moscow. Their protests came amid the demonstrations held in the run-up to Russia's rigged presidential election on March 4 which Putin easily won. The song attacked the politically subservient Orthodox Church, decried "the ghost of freedom in heaven", and beseeched the Virgin Mary to "drive away Putin, drive away Putin", before ending with some comparatively mild expletives.

A few days later, the three were arrested, and held in prison on charges of "hooliganism motivated by religious hatred or hostility". The full glory of Russian law, in all its impartiality and respect of the rights of those not yet found guilty, then unfurled: an indictment running to 2,800 pages, followed by word in early July that the defendants would have just five days to prepare their defence. By that time, however, outrage in Russia and beyond was reaching explosive levels, and a trial date was set for July 30. The girls cast themselves as dissidents in the noblest Soviet tradition. On trial, Tolokonnikova said in her closing statement, were not three musicians, but "the entire state system of the Russian Federation".

In any country, such a stunt would have caused considerable offence, and not merely among the devout. But imagine the consequences, had it occurred in the West. In the US, there would have been outrage on right wing talk radio, and much frothing on the warring cable TV news channels, while the band's PR people would have had their work cut out to prevent a cascade of engagement cancellations. Had the punk prayer been in Westminster Abbey, it would doubtless have sparked much snide commentary about how finally the C of E had become relevant to national life. In neither country, of course, would the affair have got within a mile of the courts.

Not so Russia. Perhaps there will now be a show of "mercy". When he visited London during the Olympics, Putin, the lawgiver, expressed the wish that the sentence (theoretically a maximum seven years) not be too severe. Of course, it all depends on his own definition of "severe".As it is, the three women have already been in jail for five months, ludicrously excessive punishment even were they to walk out of the courtroom today scot-free.

But then again, the girls might count themselves fortunate. The former oligarch Mikhail Khodorkovsky, initially arrested in 2003, is currently serving a sentence in a Siberian prison whose length depends on Putin's pleasure, for having shown untoward political ambitions. As for Sergei Magnitsky, the lawyer who is another poster boy for Russian "justice", he was arrested after exposing massive corruption among senior Russian officials. Having been held and tortured in a squalid Moscow prison, he died almost a year later, in November 2009.

Even that, it should be said, has not ended his ordeal. Having been initially accused on trumped-up charges of embezzlement, Magnitsky faces a final macabre distinction of becoming perhaps the first person anywhere to be tried posthumously. For their supporters at home and abroad, both Khordokovsky and Magnitsky have achieved a martyr status, which Putin could bestow upon Pussy Riot today if a severe sentence is handed down. Whatever happens though, any clemency will be strictly relative.

Putin faces the dilemma of the tyrant throughout the ages, a dilemma now playing out in especially dark and bloody form in Syria. The hardest task for an authoritarian regime is to reform itself from within. The last time the trick was attempted on the Russian landmass, by Mikhail Gorbachev, the result was the collapse of Communism. Bashar al-Assad plainly concluded from day one that any accommodation with his opponents was impossible if his Alawite sect was to retain power – even if the price was the destruction of his country.

For Putin, who by no coincidence happens to be Assad's most important foreign ally, the stakes are not quite as high. But the principle is the same. Any relaxation risks being taken as a sign of weakness, that might only embolden his opponents. If the law is wielded lightly on this occasion, the regime will be perceived as trembling before public opinion, and the next round of street demonstrations may be even more imposing. Crack down too hard however, and the legitimacy of his rule (not to mention Russia's international image that the Kremlin does care about, whatever impression to the contrary it seeks to convey) will be further damaged. Truly, it's tough being a tough guy.

r.cornwell@independent.co.uk