An Irish judge has legalised the possession of more than 100 party drugs such as ecstasy, ketamine, magic mushrooms in the Emerald Isle.

Ireland’s parliament sat late into the night on Tuesday to rush through emergency laws to close the loophole.

But the new drug laws won’t come into effect until Thursday, giving a 48-hour window of opportunity to recreational users to indulge their habits without penalty.

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The situation arose after the Court of Appeal struck down part of Ireland’s 1977 Misuse of Drugs Act after a legal challenge.

The challenge was brought by a man prosecuted for possession of methylethcathinone, a substance sold by shops that stock legal or herbal stimulants.

Irish Health Minister Leo Varadkar, a medical doctor, said legislation had been prepared in advance of the court decision, but that it would take 24 hours to pass each of Ireland’s two houses of parliament.

“We had no way of knowing what the court would decide today, but we prepared for this possibility,” Varadkar said.

“The emergency legislation I am introducing today will re-instate the status quo ante and re-control all drugs that were controlled prior to this judgment.”

The Health Minister warned that all of the briefly legalised drugs have “very significant” health risks that outweigh their recreational benefits.

Methylethcathinone was outlawed in 2011, but the Irish court found the ban to be unconstitutional as parliament had not been consulted.

As a knock-on effect, more than 100 drugs restricted by that part of the law were no longer illegal to possess.

The sale, supply, import and export of the drugs remained illegal.

The possession of older drugs such as heroin, cocaine and cannabis was not affected, the Irish Department of Health confirmed.

—with AAP.