A legal loophole means that you cannot be arrested for possession until the new legislation is passed.
It does not affect existing laws regarding the supply, possession or the sale of older, more established drugs such as heroin or cocaine, just newer ones.
The Irish minister for health is introducing emergency legislation on Tuesday night to close the loophole.
A government spokesperson said: "It is now important from both a public health and criminal justice perspective that the legislation be enacted as soon as possible."
Ireland's 1977 Misuse of Drugs Act was found unconstitutional by the Irish Court of Appeal on Tuesday morning because both houses of Irish parliament had not agreed to the new additions, meaning that the drugs currently prohibited by the Act are legal.
This includes up to 100 drugs, including "legal highs".  Health Minister Leo Varadkar said: "All carry health risks... and can lead to death."
Follow @BBCNewsbeat on Twitter, BBCNewsbeat on Instagram and Radio1Newsbeat on YouTube
Ireland has accidentally legalised ecstasy, crystal meth and ketamine.