Kava is disallowed in consumer products in Australia as of June 2007. According to the Australian Government's Office of Health Protection: "From 26 June 2007, the existing regulations on importation of kava were strictly enforced with the effect that commercial importations of kava were no longer allowed except for medical or scientific purposes. Incoming passengers who are over the age of 18 years are allowed to bring 2 kg of kava into Australia in their accompanied baggage." See http://www.health.gov.au/internet/main/publishing.nsf/Content/importation-of-kava. (thanks wj) (last updated May 6 2013)

We have been told that Kava is sold in herb shops in Brazil but that it's recreational use is very rare and unknown by the authorities. (unconfirmed) (thanks P)

Britain has banned the sale all medicines containing kava extracts. We believe raw root powder is still legal for sale, but we aren't sure. (May 2003). See: Reuters, Dec 2002. It is not currently illegal to possess kava extracts in Britain.
It also appears that kava is now banned for import or sale for the purpose of ingestion (internal use): Statutory Instrument 2002 No.3170 : The Medicines for Human Use (Kava-kava) (prohibition) Order 2002 :The Stationery Office Ltd , UK Government E1856 12/02. CropWatch.org Kava Ban Update

Canada's federal government agency, Health Canada, issued a stop order blocking the sales of kava products for human consumption in all of canada in August, 2002. As of this ruling, all products containing kava including drinks, supplements, etc have been banned for sale in Canada. Vendors in other countries regularly sell Kava products to Canadian customers and it is not illegal as a Canadian citizen to purchase or import kava products for personal use. Health Canada Natural Health Products Compliance Guide

Kava is widely available in Europe but some countries regulate its sale.

Kava products available with no age limit. (unconfirmed)

Kava supplements and products banned for sale. (unconfirmed) Reportedly, Piper methysticum is still available from herbalists.

After a handful of deaths have been reported from kava-related liver failure, Germany is considering legislation to more tightly regulate its sale.

Kava-Kava: Zulassung beschränkt

Die Zulassung des pflanzlichen Beruhigungsmittels Kava-Kava soll eingeschränkt werden. Nach Bekanntwerden von 18 Fällen von Lebervergiftung, von denen einer tödlich endete und drei Transplantationen erforderlich machten, soll das Anti-Stress-Medikament künftig nur noch in extrem verdünnter Mischung erhältlich sein."

English: Loosely translated this means that Germany wants to tighten regulations regarding kava after 18 cases of liver poisoning. One of them died and three had to undergo liver transplantation. Kava products will have to be sold in much more diluted form.
(Reference)

We have received conflicting reports about the legality of kava-containing products in Israel. One visitor tells us that Kava-containing products are legal to possess, import, and sell in Israel, but another says that a shop in Tel Aviv reported that kava is illegal in Israel. (unconfirmed) (thanks js, sm) (last updated Jan 6, 2011)

Kava-containing products have been banned for general sale since jan 01 2003. (unconfirmed) (thanks JS)

Kava-containing supplements sold at grocery stores. (unconfirmed) (thanks S)

Kava supplements and products are not specifically controlled in Norway, but we have been told that the national health council considers it a prescription drug (available only from a pharmacy) based on it's use as a psychoactive drug. (unconfirmed)

Kava is banned from being sold within Sweden, but is allowed to be imported. (unconfirmed) (thanks G) (last updated May 11 2010)

Laitan, a kavalactone pharmaceutical sold in pharmacies in Europe has been banned for sale in Switzerland. -- Source