Garda sources said reports from 12 Garda divisions across the country at 5pm yesterday indicated that no head stores had opened. Gardaí expect to have a full picture by later today.
They said the “vast majority” of head shop owners had indicated before yesterday that they had decided to shut up shop for good.
In Dublin, the biggest and most popular head shops had their shutters pulled down with signs saying they had closed.
The Dublin Head Store in Temple Bar had a closing- down sale in the run-up to the commencement of laws yesterday outlawing the sale of psychoactive substances or mind-altering drugs.
A sign thanked customers for their business and blamed negative media coverage and “public hysteria” for the closure of their store.
The Nirvana store on South William Street, which did a booming trade at weekends was also shut, with a sign saying “closed until further notice”.
The Criminal Justice (Psychoactive Substances) Act 2010 came into force just after midnight yesterday, making the sale of psychoactive substances a criminal offence, punishable by up to five years in prison.
It empowers the gardaí to issue prohibition notices to owners against selling suspected substances, which can lead to prohibition orders and even closure orders in the courts.
Gardaí attached to drug units across the country visited all 39 head shops last week and told them the act would be in place and enforced by them on Monday.
Garda sources said the “vast majority” had indicated they did not intend to continue trading given the tiny number of products they could still sell.
Last May, before a ban on certain products was brought in, there were 102 head shops in the country.
Justice Minister Dermot Ahern said: “This act is indicative of my determination that those who engage in the sale of unregulated psychoactive substances for human consumption will not be allowed to escape the rigours of the law.
“The sale of such substances, especially to the younger members of our society, is a dangerous trade which operates without regard to the consequences for the health and safety of its customers or of society generally.”