40 Futures is a speculative fiction series about the criminal justice system.
Perp Walk
“Alright, walk on the mat as you’d normally walk,” commanded officer Trent. “One at a time, now. We can’t have more than one on the mat at the time.”
In the back of the police substation, the officer took a seat behind a monitor with a split screen. The left side was looping a video of green, cartoonish outlines of feet walking a step at a time. The right side was blank.
The six assembled men of similar height and weight looked with curiosity at the rubber mat laid out in front of them—yellow and black cords snaked on the cracked concrete floor to the officer’s desk. The buzz of fluorescent lighting droned in the background.
As the first man walked across the mat, red feet lit up the right side of the officer’s screen.
“Now, walk back across the way you came,” the officer ordered.
The man did as he was told. The feet on the screen were still red.
“Alright, you’re free to leave.” He didn’t look up from the screen as he waved the man away. “Next!”
Another, and the man after him, all did the same. All producing red, cartoon feet on the right side of the officer’s screen. They too were excused.
The fourth man took three steps on the mat before the cartoon feet turned green. Trent’s heart jumped and his eyes went big as he looked up from the screen at the man, making eye contact with him for the first time.
“Do it again,” he said pointing at the man on the mat trying to hide his excitement, “walk back across the mat a few more times.”
Dutifully, he marched back and forth, the feet on Trent’s screen remained green. He looked closer: the pronation of the right foot, the slight drag of the left heel--it all matched up. Could there be another person in the city with the same walk? Sure, but what were the chances they were leaving the convenience store at Franklin and Eutaw right after it was held up? Constitutionally insignificant, he thought. By his estimation, the city’s investment in smartcrete sidewalks gave him enough for an arrest.
Trent dismissed the other two men in the lineup and looked at the man on the mat, who stared back blankly. He unhooked the cuffs from his belt and started to read the man his rights as he slowly walked him to his holding cell.
Links from the podcast commentary
Smart cities are surveilled cities. (Foreign Policy)
Towards smart concrete for smart cities: Recent results and future application of strain-sensing nanocomposites. (Iowa State University)
Forensic gait analysis. (NIH)
A systematic review of gait analysis methods based on inertial sensors and adaptive algorithms. (Gait & Posture)
A case in Florida demonstrates the problems with using facial recognition to identify suspects in low-stakes crimes. (Slate)
Forensic Science in Criminal Courts: Ensuring Scientific Validity (PCAST)
40 Futures: v1.04 Perp Walk