So it turns out we already have plenty of cameras on the street. They’re not government cameras, but rather cameras owned and operated by private individuals and businesses. In a bout of public spiritedness, these pedestrians and businesses willingly shared their videos with law enforcement. Even if the crime had not been so notorious, the police could expect public cooperation — what merchant wouldn’t share his surveillance tapes to aid in a murder investigation?

So what do we gain by having the government run its own cameras? That would mean the police wouldn’t need to turn to the public for help. This would create efficiencies, but it seems the public responded pretty efficiently last week.

Here’s one big difference between the sort of cooperative surveillance displayed in Boston last week and London’s Big Brother approach: The American system requires the willing participation of the public, or maybe warrants from a judge — or at least subpoenas.

Give the government eyes on every street corner, and you mostly aid the ability of law enforcement to track us without public cooperation, warrants or legal paperwork.