The Diet on Wednesday passed a bill revising the pharmaceutical affairs law to tighten controls on quasi-legal drugs after a series of traffic accidents involving drivers high on them.
The House of Councilors approved the bill, which was earlier passed by the House of Representatives.
The revised law allows authorities to ban the sale nationwide of so-called "dappo" drugs. Under the current law, a government order to ban the sales of quasi-legal drugs only covers a retailer that has been inspected by narcotics officers.
Under the amended law, the government will disclose the names of the drugs to be banned and a description of their packaging in its official gazette or on its website.
The new law includes a clause banning advertisements for the drugs and sets penalties of imprisonment for up to one year or a maximum fine of up to ¥1 million for those who violate the ban.
The Ministry of Health, Labor and Welfare has so far asked Internet service providers to delete websites where such drugs are sold. The revised law makes clear that the ministry has the legal powers to make such requests, and says the providers will not be held financially liable for online ads lost by taking down the websites.
The government is scheduled to promulgate by the end of November the revised law, which will come into force 20 days later.
The issue of potentially harmful drugs that are not proscribed by law gained public attention after a number of traffic accidents involving drivers thought to have taken them.
In one such case, a driver has been indicted on charges of hitting pedestrians in Tokyo's Ikebukuro district on June 24. A woman was killed and six people were injured in that incident.