I have never understood how this was effective against a determined adversary. An arbitrary limit like 100ml is pointless when there is no limit to the number of times you can pass through the checkpoint.
> An arbitrary limit like 100ml is pointless
Do you know that the 100 ml liquids gets scanned in the Heathrow airport? Many times they used to do a secondary scan too after the primary scan. I recall this very well because many times I was made to wait longer after my carry on arrived because they wanted to put the liquids through a secondary scan.
Oh. So it was a security measure? I honestly thought it was a way to force you to spend money on things on the airport or abroad. Like shampoo, water, etc.
How about an undetermined adversary? Security is all about raising the cost of an attack, not about preventing one altogether
In many countries (Canada included) if you pass through security into the international terminal, you have to 're-enter the country' back through customs and immigration if you don't get on your flight.
It's also hilarious that the limit is the very metric 100ml, and not some even number of freedom units like 3 or 4 fluid ounces, like Jesus, George Washington, and bald eagles would have wanted.
I'm sure that going through security 5 times for the same flight is bound to trigger some extra screening and even if it doesn't, each time you cross through increases the likelihood of getting caught by the normal process.
Don't get me wrong, I'm sure a large part of it is just security theatre, but part of it is also just to be enough of a deterrent that a would-be terrorist chooses a different target.