By Saima Baig In the last few weeks or so, a fracas has unfolded in the UK media. Charlotte Caldwell, from Northern Ireland, had cannabis oil which was confiscated at Heathrow Airport, because it contains a psychoactive substance called tetrahydrocannabinol (THC – the psychoactive element in marijuana), high concentrations of which are illegal in the UK. The reason she had the oil was that her son Billy suffers from severe epilepsy and a doctor in Northern Ireland had prescribed it for him in 2017 – the first time someone was…