Earlier quoted context omitted.
That's not quite right. Legislators certainly can keep up; all they need to do pass a broad ban on chemicals with the undesired empirical properties.
You can't legislate a state of mind, and people have different reactions to different substances, so I'm a little confused as to what form this "broad ban" would take.
http://www.legislation.gov.uk/ukpga/2016/2/contents/enacted
https://en.wikipedia.org/wiki/Psychoactive_Substances_Act_20...
But also the UK has rapid powers to add a substance to the schedule in the Misuse of Drugs Act. Here's a recent list: https://www.gov.uk/government/publications/controlled-drugs-...
Here's schedule 2. I don't know how often this gets updated: http://www.legislation.gov.uk/ukpga/1971/38/schedule/2
> You can't legislate a state of mind,
You can legislate "intoxication", although the methods for doing so are pretty crude at the moment.