Why does spiking often go unpunished?

ITV News - What You Need To Know

There’s an epidemic of spiking that’s sprawling across the UK.
And yet, official reports and convictions of the crime remain low.
Often, by the time the victim comes around, it may be too late to gather crucial evidence, leaving them helpless.
So, what can be done? Why does spiking often go unpunished? And how safe are you when out on the town?
ITV News Reporter Sangita Lal tells Sally Bidulph what you need to know…