The Eurasian Economic Union, which Russia heads, allows foreigners the right to bring banned substances into the country provided they have supporting medical documents written in Russian.
Incredibly, according to the Moscow Times, that extensive list includes cocaine, cannabis and heroin.
On Tuesday, the World Cup organising committee pledged to have police on duty who will verify the paperwork of those carrying around such drugs.
They said: "Security officers will monitor the enforcement of rules for carrying prescription drugs to stadium grounds at checkpoints."
Fans will, of course, also have to sign a customs declaration when they enter the country.
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