Taking ecstasy, ketamine, magic mushrooms and so-called 'head shop highs' has become legal in Ireland - for one night only.
A landmark case before Dublin's Court of Appeal has struck down legislation banning the possession of more than 100 drugs and substances. The surprise move forced the Irish government to sit late into the night to rush through emergency laws to shut down the loophole.
The Misuse of Drugs (Amendment) Bill 2015 was introduced by Minister for Health Leo Varadkar following the striking down by the Court of Appeal of the ban of the drugs, which included benzodiazepines and various psychoactive substances.
The government was forced to act after a decision by the Court of Appeal on a challenge to the Misuse of Drugs Act 1977.
The case was brought by a man prosecuted for possession of methylethcathinone in 2012. He denies criminal charges of supplying the substance and argued the regulations were unconstitutional.
The substance also known as 4-mec or snow blow is one of around 100 brought under a blanket ban in Ireland four years ago, which forced head shops around the country out of business overnight.
The three-judge court unanimously agreed a regulation making the possession of methylethcathinone illegal was invalid, as it was unconstitutional.
Because of the way the laws are drawn up, the ruling had the knock-on effect of temporarily legalising the possession of other drugs in the same category.
Health Minister Leo Varadkar yesterday warned anyone tempted to take advantage of the temporary decriminalisation to think about their health.
"They all have very significant health risks that outweigh any perceived recreational benefits," he said. "We had no way of knowing what the court would decide today, but we prepared for this possibility."
In a statement, the Department of Health said there was always a degree of uncertainty about the outcome of court cases.
"The outcome of this case does not affect existing laws regarding the supply, possession or sale of older drugs such as heroin, cocaine or cannabis," it added.
"It does affect the possession of certain newer psychoactive substances which have been added to the Misuse of Drugs Act 1977 by successive governments.
"However, we are advised that sale and supply of psychoactive substances remains an offence under existing legislation."
The Bill will be passed by the Seanad today and then go to President Higgins for signing.