Number Plate Recognition and Traffic Enforcement

In one line

Parliament wrote the camera into the statute, so this is what a lawful automated system looks like.

What the technique does

Capture. A camera photographs the front or rear of a vehicle, usually with infrared illumination so that it works at night and is not defeated by headlights.

Plate location. The software finds the rectangle of the plate in the frame.

Segmentation. It separates the characters.

Optical character recognition. It reads them and produces a registration number as text.

Lookup. The number is compared with a register: the vehicle records, a list of stolen vehicles, a list of vehicles without insurance or a valid fitness certificate, or a list of vehicles wanted in a case.

Where it fails. A dirty, bent, obscured or non-standard plate; a decorative font; snow, rain or glare; a plate at a sharp angle; and the reliable confusions between characters that look alike, so that a single misread character produces the record of a different vehicle altogether.

Why this one is different: section 136A

Section 136A of the Motor Vehicles Act 1988 is headed "Electronic monitoring and enforcement of road safety" and it says that the State Government shall ensure electronic monitoring and enforcement of road safety on national highways, State highways, roads or in any urban city within a State which has a population up to such limits as may be prescribed by the Central Government, and that the Central Government shall make rules for it "including speed cameras, closed-circuit television cameras, speed guns, body wearable cameras and such other technology". The Explanation defines a body wearable camera as a mobile audio and video capture device worn on the body or uniform of a person authorised by the State Government.

Note the date. Section 136A was inserted by the Motor Vehicles (Amendment) Act 2019 (Act 32 of 2019), section 47, with effect from 15 July 2021, which is nearly two years after most of that amending Act came into force on 1 September 2019. It is a good illustration of the rule that commencement is checked and not assumed. Section 137 was amended at the same time to give the Central Government power to make rules for the limits of an urban city under section 136A(1) and for the electronic monitoring under section 136A(2).

So the enabling law names the device. That is exactly what facial recognition lacks, and the contrast is the most useful thing in this chapter.

The evidential hook: section 183(3)

Section 183(1) punishes driving in contravention of the speed limits under section 112, with a fine of not less than one thousand and up to two thousand rupees for a light motor vehicle, not less than two thousand and up to four thousand rupees for a medium or heavy goods or passenger vehicle, and impounding of the driving licence under section 206(4) for a second or subsequent offence.