One tree is not a forest. A million trees is a forest. Nobody can tell you which single tree delineates the difference. That doesn’t stop us from calling a tree a tree and a forest a forest.

The tech community has this idea that it’s impossible to make laws affecting such concepts that cannot easily be expressed as an algorithm giving boolean answers. But in reality, that’s exactly what jurisprudence does for a living. Otherwise there would be no need for lawyers and judges and juries.

The “I know it when I see it” quote is, obviously, one coined by a judge, and a supreme one at that. It became famous for both being somewhat true, and for leaving us wanting for something better. And even though the definition of pornography has somewhat advanced since then, and become somewhat less relevant, there still is a gray area: some gangbang on pornhub is probably porn. A bag of Doritos is not porn. In between are the image of Kim Phuc, Michelangelo’s David, and many a work of art. But the existence of that gray area does not negate the possibility to definitively say that the bag of Doritos is not porn, as far as the law is concerned.

The problem with laws that allow for "I'll know it when I see it" is that - The need to be vague/broad enough to allow anything that could be <thing> to be classified as <thing> under the law - The government actors are well know for acting in bad faith, ruining the lives of people that did nothing wrong because the law allowed for it.

A teenage couple tried as adults for child pornography because they sent each other naked pictures of themselves. That is clearly not what the law intended, but the state went after them for it anyways.

Vague/overly-broad laws can be abused. Any law that can be abused will be abused.

Legislation requires more precise definitions if it is to be useful in court.

You'd be amazed how much legislation just says "reasonable" and leaves the court to the details.

As some one said to me "as so many MP's are lawyers its a favour (billing opportunity ) for their lawyer friends"

There are quite a few laws concerning both pornography and forests, and civilization has steadfastly refused to die.

The view of the Man on the Clapham Omnibus is useful in court but not very precise...

The solution generally is "we form a department that employs qualified people and scores entities on quality X", then the law says "entities with less than 50% X as determined by the department for X scores shall not appear on the first page of results". As a programmer you should know that all problems can be solved with enough levels of indirection :) .