That President Boris Yeltsin enjoys a drink is far from being a revelation. He himself has never sought to hide the fact. How much he drinks and to what effect is from time to time, as now, a matter for speculation.


Opinion is divided as to whether his energetic conducting and spirited rendition of "Kalinka" in Berlin were the result of a glass too many of champagne or simply his own characteristic exuberance. Whatever the cause, the damage was limited to the eardrums of the musically sensitive and the ruffled dignity of a few embarrassed aides.


The Ireland incident, when Yeltsin failed to emerge from his plane for talks with Albert Reynolds, was more serious. It was not just the fact that this was an appalling diplomatic gaffe -- which it undoubtedly was -- for this can be put right in time. It was not only a question of drunkenness. Whether Yeltsin was or was not drunk is known for certain by only a few people on board the plane.


The crux of the matter is that he was incapacitated. For whatever reason, be it over-indulgence, over-tiredness or an over-protective bodyguard, Yeltsin was unable to carry out his duties. And when that happens to someone as important as the President of Russia, alarm bells are certain to start ringing.


His political opponents, never ones to miss an opportunity for humbug, have made noisy demands for the President to undergo medical tests. These calls clearly have more to do with efforts to bring about Yeltsin's humiliation than with ensuring the country's stability, but they do nonetheless raise an important issue.


There is no provision for anyone to take over Yeltsin's duties if he is temporarily indisposed, through ill health, or for any other reason.


Since the fall from grace of Alexander Rutskoi, Russia has had no vice president. In the event of Yeltsin's death, it would fall to the Prime Minister, Viktor Chernomyrdin, to take over pending a new election, but this does not deal with the issue of incapacity.


This is not to suggest that Yeltsin is losing his touch. But every head of state needs a stand-in, if only to ensure the smooth transition of power. As things stand, there is no mechanism or due process to determine the succession of power if the president should prove incapable of exercising it. If such a crisis should occur, the country would be left with a power vacuum or a figurehead. Neither case augurs well.


Incapacitated leaders are nothing new to Russia -- one need only look back to Konstantin Chernenko or Leonid Brezhnev. But at this crucial time in Russia's history, the last thing the country needs is uncertainty about the control or transfer of its leadership.