The Economist - 04.12.2021

The Economist December 4th 2021 United States 43

Crimetech

Shot spotty

W

alkaroundoneofthepoorerneigh­
bourhoodsofChicagoandlookatthe
street­lamps. Youwillseethat manyof
themhaveprotuberancesstickingseveral
feet above the light. These are micro­
phones operated by ShotSpotter, a firm
withitsheadquartersinCalifornia.They
arespreadovera largepartofChicago,and
theycapturethesoundsofgunshots.Algo­
rithmspickoutthesounds,whicharethen
verifiedby humanslistening in froma
controlcentreinWashington,dc. Triangu­
lating the sounds from several micro­
phonesrevealswherethegunswerefired.
Policearealertedandrushtothescene,
quickerthaniftheyhadtowaitfora 911
call—especiallyonethatmaynotcome.
Thatistheidea,anyway.Overthepast
25 years, ShotSpotter’s technology has
spreadacrossAmerica.Itisnowusedin
morethan 100 cities.Chicagoisitsbiggest
market,withthepolicedepartmentpaying
around$11ma yearfortheservice,account­
ingforalmosta fifthofthefirm’srevenue.
InthepastyearChicagohashad 795 homi­
cidevictims,almostallfromshootings.
Theuseofthesensorsisincreasingly
controversial,inChicagoandelsewhere.
InAugusttheChicagoOfficeoftheInspec­
torGeneral (oig), acity watchdog, pro­
duceda reportquestioningtheusefulness
ofthetechnology.OnNovember12ththe
city council’s public­safety committee
helda specialhearingtoquestionthepo­

lice  and  the  firm  about  the  concerns.  On

November 3rd Baltimore decided to renew

its contract, but narrowly: the mayor, Bran­

don  Scott,  declared  that  he  is  the  “biggest

sceptic”  and  that  evaluations  would  con­

tinue.  Other  cities,  such  as  Charlotte,  in

North  Carolina,  have  ended  their  con­

tracts. Is the technology worth it? 

According  to  the  oig,  of  just  over

50,000  alerts  generated  by  the  system  be­

tween  January  2020  and  May  2021,  only

about 2% led to the police stopping some­

body.  Only  0.4%  of  alerts  resulted  in  ar­

rests and even fewer the recovery of weap­

ons.  A  separate  study  by  the  MacArthur

Justice Centre, a civil­rights law firm affili­

ated with Northwestern University, found

that  in  just  10%  of  cases  generated  by  the

system  could  police  find  evidence  of  a

shooting,  such  as  spent  cartridge  cases  or

bullet holes. 

And yet each alert is treated as equiva­

lent  to  a  shooting  in  progress,  says  Jona­

than  Manes,  of  the  MacArthur  centre,

which means multiple police officers rush

to the scene. In Chicago police respond to

roughly 60 alerts per day. Those resources,

as well as the money spent on the system

itself,  could  be  used  to  investigate  crimes

that have been reported, he says. Less than

half of murders in Chicago are solved.

“ShotSpotter technology does not deter

crime  or  shootings,”  says  Ray  Kelly  of  the

Citizens Policing Project, a group in Balti­

more  that  presses  for  closer  relations  be­

tween  the  police  and  citizens.  “So  what  is

the benefit?” In Chicago, police­reform ac­

tivists  point  to  the  trial  of  Michael  Wil­

liams, a 65­year­old black man who was ar­

rested last year on charges of murder. The

prosecution  presented  evidence  from  the

ShotSpotter  system  to  argue  that  he  had

killed  a  young  man  in  his  car.  The  case

proved flimsy, and in July Mr Williams was

released. In another case, in March, an un­

armed 13­year­old boy was shot and killed

by police responding to an alert. 

Deborah Witzburg, who was deputy in­

spector­general for public safety in Chica­

go until November 12th, points out that the

city’s police department, which has a long

history  of  abuse  allegations,  has  a  “legiti­

macy deficit”. Sending armed cops in num­

bers  to  respond  to  computerised  alerts

seems unlikely to help build trust.

The firm defends the effectiveness of its

system.  It  points  to  plenty  of  cases  where

ShotSpotter alerts resulted in arrests or the

timely rescue of gunshot victims. But there

is  little  independent  evidence  that  it  re­

duces crime overall. One study, published

in  April  in  the  Journal of Urban Health,

found  that  “implementing  ShotSpotter

technology  has  no  significant  impact  on

firearm­related  homicides  or  arrest  out­

comes”.  Microphones  on  street­lightsare

all very well, but they are no substitutefor

information gathered from humans.n

C HICAGO
Are gunshot-detecting microphones
worth the money?

Atriumph of triangulation, perhaps

Abortionrights

Roe’s last stand

A

mericans on bothsides  of  the  abor­

tion  debate  have  been  here  before.  In

1992  defenders  of  the  right  to  abortion

braced  themselves  for  the  worst  when,  in

Planned Parenthood v Casey,it  seemed  on

the cusp of erasure. Then, to the dismay of

abortion  opponents,  five  justices  forged  a

coalition to preserve Roe v Wade, the ruling

in  1973  that  established  abortion  rights.

This  time,  in Dobbs v Jackson Women’s

Health Organisation, a  surprise  ending

seems  unlikely.  In  oral  arguments  on  De­

cember 1st, the most conservative Supreme

Court  in  a  century  sounded  intent  on  re­

writing—and  probably  abandoning—a

half­century­old constitutional liberty.

Dobbsinvolves a ban by Mississippi on

most abortions after 15 weeks of pregnan­

cy. (There are exceptions in cases of danger

to a woman’s health or severe fetal abnor­

mality,  but  not  in  cases  of  rape  or  incest.)

The  law,  adopted  in  2018,  was  blocked  in

lower  courts  as  a  violation  of  the  protec­

tion Roeand Caseyprovide to abortion be­

fore fetal viability (about 24 weeks). When

Mississippi petitioned the Supreme Court

in June 2020, it made the relatively modest

point that some pre­viability bans may be

constitutional. But when the state filed pa­

pers  a  year  later—after  the  conservative

Amy Coney Barrett replaced the late, liberal

Ruth  Bader  Ginsburg—its  tune  had

N EW YORK

Nearly a half-century after Roe v Wade,

abortion rights are hanging by a thread