The trial of a man charged with possessing explosives in the lead up to the G20 economic summit in Toronto began on Monday, with lawyers arguing his charter rights were violated when police detained him and searched his property.

Sonne was arrested in June 2010 and charged with possession of explosives for an unlawful purpose, possession of dangerous weapons and intimidation of a justice system participant by threat and mischief.

Four of those charges were later dropped by the Crown. Sonne still faces one charge of possession of materials used to make explosives and another charge of counselling to commit mischief.

Police have alleged that Sonne, an independent internet security expert, planned to detonate a homemade explosive device in downtown Toronto while leaders were in town for the G20 summit.

Supporters of Sonne have said he was just trying to test how far police would infringe on civil liberties in the name of security. Sonne spent 11 months in jail on G20-related charges after being arrested last June.

According to court documents, Sonne claims his rights were first violated when police stopped him in June 2010 while he was taking pictures downtown Toronto of the security fence being erected. Police have admitted that they threatened to arrest him for jaywalking, but that that was just a ruse to get Sonne to identify himself. 

Police later obtained a search warrant based on information gleaned from Twitter and Flickr accounts linked to Sonne.

But Sonne claims that the information police used to get the warrant was misleading and "contained a number of falsehoods and inaccuracies, engaged in speculation and relied on information of dubious reliability."

He said the warrant was, in part, based on "wildly speculative" claims. Those claims included that some of the objects pictured on the Flickr website were projectiles capable of being fired from a potato cannon and that he was involved in a criminal plot to destroy surveillance cameras.

According to the court documents, Sonne, prior to the search of his house, was detained by police and gave them information that he had number of recreational potato cannons at a family cottage.

He also gave them information about chemicals at his home —chemicals that could be used to produce explosives.  But Sonne also claimed that he had an interest in model rocketry and that some of the chemicals are used in the manufacture of fireworks and model rocket fuel.

Sonne also said police, in order to obtain a second search warrant,  falsely claimed that Sonne had an explosive compound known as HMTD as well as a home-made detonator at his house.

Sonne's preliminary hearing and bail applications were covered by a sweeping publication ban and he said on Monday that he was pleased the proceedings could now be published.

The trial continues Tuesday.

With files from The Canadian Press