Christopher Miller was charged with mischief for writing “Shame on you” in charcoal on a sidewalk at police headquarters.

National Post photographer Brett Grundlock was charged with obstructing police and unlawful assembly while doing his job.

And Robert Gamble was charged with disturbing the peace after he yelled “Arrest the war criminals. Investigate 9/11.”

The Crown dropped all these charges, and more, on Monday as hundreds of people paraded through Ontario Court in the aftermath of the Group of 20 summit protests that rocked downtown Toronto on June 26 and 27, during which some vandals torched police cars and smashed shop windows.

The sheer flimsiness of some of the charges ought to embarrass the Toronto police and other forces that arrested more than 1,000 people, penning them up in wire cages for much of the weekend.

Ultimately only some 300 were charged. And while the 17 alleged ringleaders and others still have a date with the courts, prosecutors were eager to drop or “divert” charges for nearly 100 people if they agreed to contribute to a charity, do community service or sign a peace bond.

This winnowing process reflects well on Ontario Court, and its reluctance to criminalize dissent. But it does nothing to ease concerns about Prime Minister Stephen Harper’s unwisdom in holding the G20 in downtown Toronto, turning it into an armed camp of empty streets. Or Premier Dalton McGuinty’s decision to grant the police enhanced powers of arrest without properly informing the public. Or the police strategy that first let vandals run amok, then cracked down on non-violent protesters.

These are far-ranging matters of political responsibility and civil rights that only a full inquiry can properly address, not the slew of low-level probes now underway by the Toronto police, the Police Services Board, the Ontario ombudsman’s office and Ontario’s new Independent Civilian Review and Public Complaints Process. Each is looking at a piece of the problem.

What’s needed is a broad public inquiry by Ottawa or Queen’s Park into this wretched chain of events, from the Prime Minister’s fateful decision to turn Toronto into an armed camp, to police tactics that ranged from laissez-faire to abrupt mass arrests. We deserve a full accounting.