Five Western countries -- the US, Canada, Britain, Italy, and Sweden -- have formally objected to Bolivia's rejoining the 1961 UN Single Convention on Narcotic Drugs with a reservation that allows for the traditional habit of coca leaf chewing, the Transnational Institute reported last Friday. The move is the latest twist in the Latin American nation's effort to remove the international proscription on the ancestral habit.

But the Western objections are far from sufficient. Another 58 signatory countries would have to object by next week to block Bolivia's bid, and there is little sign of that happening.

[Update: On Wednesday, Russian President Vladimir Putin submiltted a bill to the Duma objecting to Bolivia's reservation, but it wasn't clear if that amounted to a formal objection.]

Coca leaf, the raw material from which cocaine is produced, has been used with little ill effect as a hunger-suppressant and mild stimulant for thousands of years in South America's Andean region. It was included as a proscribed substance in the 1961 Convention based on a 1950 study that has been found to be unscientific and blatantly prejudiced. The 1961 Convention called for the chewing of coca leaf to be phased out by 1989.

Led by former coca grower union leader Evo Morales, Bolivia tried in 2011 to amend the 1961 Single Convention to remove the provision requiring it to ban coca leaf chewing. If no countries objected, the request would have been automatically granted, but the US, supported by the International Narcotics Control Board organized a "friends of the convention" group to rally against the move. In all, 18 countries objected to Bolivia's request.

Among Latin American countries, only Mexico's conservative government objected. Colombia objected at first, but withdrew its objection, while Costa Rica, Ecuador, Uruguay, and Venezuela went on record supporting Bolivia's request even though they weren't required to. The objecting countries were all European, except for Canada and the US and Japan and Singapore.

Following the failure of its effort to amend the 1961 Convention, Bolivia withdrew from it and requested re-accession with a reservation regarding the coca chewing provision. The Convention allows for such a procedure, which can be blocked only if one-third of the member states object. There are 184 countries that have signed the Convention, meaning 62 must object to stop Bolivia's re-accession.

So far, just a few have done so. Other countries have only until January 10 to weigh in.