Is it acceptable for someone to run over peaceful protesters? When new regulations being proposed say it is, perhaps it\u2019s time for technologists to see how they can help.\nGiven recent tragedies, how can peaceful protesters be protected? How can technology help protect lives? Could a portable, IoT system help safeguard freedom of speech?\nBackground\nThe First Amendment is clear. \u201cCongress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.\u201d\nMartin Luther King led\u00a0The Great March on Washington\u00a0in 1963. The purpose of the march was to advocate for\u00a0civil and economic rights\u00a0for\u00a0African Americans. At the march,\u00a0Martin Luther King Jr., standing in front of the\u00a0Lincoln Memorial, delivered his historic \u201cI Have a Dream\u201d speech in which he called for an end to racism. None of the protesters was run over by a car.\nLegislation\nA Rhode Island bill proposes that a \u201cprovide that a person driving an automobile who is exercising due care and injures another person who is participating in a protest or demonstration and is blocking traffic in a public right-of-way shall be immune from civil liability for such injury.\u201d This perspective is even shared in the news and by some\u00a0politicians.\nGiven recent events, it is frightening to think of the injuries and deaths that may be caused. Duane Clinker was on many picket lines, in many tense situations. He\u2019s seen picketers hit by cars. He\u2019s seen guns drawn. \u201cIt\u2019s very important,\u201d said Clinker, \u201cnot just to not have a chilling effect on free speech, but to not have permission, in effect, on using a two thousand or three thousand pound object to hit somebody.\u201d\nIoT-based protection for\u00a0protesters\nWhat\u2019s needed is a portable system that can be easily set up, detect dangerous vehicles and immediately alert protesters so they can get out of harm\u2019s way.\nMagnetic sensors are a good candidate for detecting vehicles as most vehicles have significant amounts of metals in their chassis. They detect cars and their speed by changes in the earth\u2019s magnetic field above the sensor. Honeywell offers a wide range of such sensors.\nLight based sensors use cameras to capture texture, color and contrast information to detect oncoming vehicles. Light Detection And Ranging (LiDAR) sensors such as those from NXP measure the distance to an object by calculating the time taken by a pulse of light to travel to an object and back to the sensor.\nMobile app\nWalkSafe is an Android app developed by researchers at Dartmouth College and the University of Bologna in Italy. It uses the smartphone\u2019s camera to detect oncoming traffic with machine-learning and image-recognition algorithms to identify the fronts and backs of vehicles. It takes into account varying light conditions, phone tilt, and blur. When detects a car approaching at 30 miles per hour or faster, the app vibrates the phone and makes a sound to alert the distracted user. The Smartphone Sensing Group offers more details on this approach.\nAlerting pedestrians\nA solution requires two components: a means to detect an oncoming vehicle and the capacity to alert a large number of protesters. An interesting approach developed by FabLab in a different context shows how this could be done. It uses SMS alerts to notify villagers about flash floods upstream. In a similar manner protesters would subscribe to a safety alert from a sensor that detects vehicles that might injure or kill them.\nSuch a solution could also be used to protect pedestrians against \u00a0the scourge of terrorist attacks with vehicles against innocent civilians such as those recently in Barcelona, Nice and London.\nIt\u2019s vital to prevent free speech and protesters from being run over. IoT offers the building blocks, but someone has to put them together into an affordable solution.