Getting aerial surveillance off the ground in Baltimore

At a City Council hearing last week, advocates and opponents of aerial surveillance presented a false choice between privacy and public safety. Truth is, with a little creativity and compromise, Baltimore can have both.

Aerial surveillance consists of a Cessna prop plane flying in public airspace with a battery of cameras taking what amounts to wide angle, low-resolution video of a large swath of the city.


The company promoting this apparatus is wrong to expect the city to grant the police department — not exactly an institution brimming with public trust these days — a blank check to surveil the city whenever and for whatever reason it wants. Instead, Baltimore should limit the use of aerial footage to the investigation of serious crimes, require written judicial approval in those cases and provide for periodic community review.

Citizens are understandably skeptical after the train wreck that prompted this debate last time around. In 2016, the police department got caught running a “pilot” that no elected official was apparently told about in advance.


It did not matter that the funding came from philanthropists who have also supported the ACLU and abolishing cash bail, the same benefactors who funded a Johns Hopkins public health initiative to deliver eyeglasses to thousands of city schoolchildren. The cloak of secrecy and how the program was discovered were too much for Baltimore to stomach.

But, with a fourth consecutive year of record violence, our city cannot afford to discard potentially good ideas just because they were badly presented.

Aerial surveillance could be a potent tool to solve violent crimes. Admittedly the raw footage alone is of modest value: it shows blurs of unrecognizable dots and rectangles, which happen to be people and cars, moving about the city. But investigators can follow a blur tied to a crime to determine where the subject came from and went. And when that dot or box passes a street camera at a particular time, police have an opportunity to get a closer look.

The tandem of aerial footage that traces the path of “dots of interest” coupled with a sprawling network of higher-resolution, ground cameras could significantly improve clearance and conviction rates.

Similar to body cameras, this new investigative tool could also make it easier to contest or verify the statements of law enforcement and would give defense attorneys a clear method to exonerate the innocent.

At the same time, this “eye in the sky” raises serious and unprecedented privacy concerns that must be addressed. Earlier this summer, in Carpenter v. United States, the Supreme Court ruled that police have to get a warrant if they want a significant interval of cell tower location data, even though a private company (the cellphone carrier) collected it. Part of the court’s rationale was that the Fourth Amendment protects against “searches” that yield information that is, like here, “detailed, encyclopedic, and effortlessly compiled.” Under the logic of this landmark decision, police use of aerial surveillance footage could be declared unconstitutional without adequate safeguards.

But we do not have to wait for a court to strike down the warrantless use of aerial surveillance; we can proactively adopt measures to protect individual and community privacy and shield use of this new technology from a likely and legitimate legal attack.

How might a limiting protocol work?


First, the city would establish stringent rules permitting review and use of aerial surveillance solely to help solve certain enumerated crimes starting with homicides. This is how Maryland’s wiretapping law works, allowing police to intercept phone calls only for certain kinds of investigations.

Second, police would have to convince a judge to sign a warrant based on probable cause before they could get their hands on any surveillance footage (except in the case of an ongoing emergency such as a carjacking, child abduction or active shooter scenario).

Finally, every six months or so, the city would publish an annotated list of all cases in which surveillance was obtained, indicating whether or not the crime was solved. Baltimore should, after all, periodically reevaluate whether the fiscal costs and privacy concerns are worth it.

This approach circumscribes the use of an untested innovation, it guarantees vital judicial oversight, and it allows the community to meaningfully audit the program to assess its overall value each year.

It also gives our city a promising new tactic at a time when current strategies are manifestly failing.

Thiru Vignarajah, the former deputy attorney general of Maryland, was a federal and city prosecutor in Baltimore and served as law clerk to Justice Stephen Breyer. His email is