A criminology expert has disputed a key argument made by the Japanese government to justify the controversial conspiracy bill, which introduces penalties for the planning of certain crimes.

The government has said the bill is needed to ratify a U.N. treaty on international organized crime and that it would boost counterterrorism efforts ahead of the 2020 Tokyo Olympics.

But Nikos Passas, a professor at Northeastern University in Boston who drafted a legislative guide for the U.N. treaty, takes issue with the proposition that the purpose of the treaty is to tackle terrorism.