Law on reflective and tinted car windows is opaque

When the Inspector-General (IG) of Police David Kimaiyo instructed his officers to impound vehicles with tinted windows this week, Kenyans went abuzz pointing out that there is no law against it.

The IG then clarified that his directive only affected public service vehicles since the “Traffic Act Cap 403 S54 A 1&2 is clear regarding tinted PSV windows & Section 30 on windscreen & windows of [all] motor vehicles with reflective properties”

I checked that law and, unfortunately, it is actually not clear! This is what it says in the sections that the IG referred to: “The windscreen and windows of every motor vehicle shall be kept free from the application of any material which has, or is capable of having, reflective properties; … A person shall not drive or operate a public service vehicle that is fitted with tinted windows or tinted windscreen …”

“Tinted” means shaded, coloured or treated in a similar manner so that the persons or objects inside are not ordinarily seen clearly from outside.”

It sounds clear but from a scientific point of view it is quite vague; for starters, even clear glass is reflective — you can see your image in it quite easily, can’t you? Secondly, most vehicles come out of the factory with faintly tinted windows. The question then is, how faint is permissible by this law?

WHAT MINIMUM?

To be clearer, the rules should state the limits of reflectance and transmittance of the glass. That is, what minimum amount of light must pass through the window glass, and what maximum is allowed to reflect?

I saw similar rules from a different country and they stated that the glass must allow at least 35 per cent of light to get through and must not reflect more than 21 per cent. That is something that can be tested scientifically; but it is also not perfect.

Which light is the law talking about? Green, yellow, red or blue? So-called white colourless light comprises all the colours of the rainbow. And they are not seven! They are infinite in number.

The nature of glass is that it reflects and transmits different percentages for different colours. It has higher reflectance for longer wavelength (reddish colours) than for shorter ones (bluish colours).

This is the reason a car gets very hot inside when left under sunlight. It is also the working principle of a greenhouse. Once sunlight gets inside, it is absorbed by the items in there; as a result they warm up and emit infra-red “light”.

More than 50pc of this infra-red is reflected back into the car by the glass – it is therefore trapped and cannot get out. Consequently, the car continuously accumulates the heat and becomes much hotter than the surrounding.

With these technicalities in mind, a good lawyer can argue in court that the rules on tints and reflective car windows are not clear and are, therefore, difficult to obey. It would be advisable for the Transport ministry to revise the rules before we get to that point.

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