The BCA insisted that they did have evidence and went on to publish it. This "evidence" was promptly demolished by various bloggers: (see here for one of the demolition jobs and links to others)
But here's the thing:
Simon Singh also pointed out that chiropractic manipulation is not risk free and may, for example, be a cause of stroke
Worse still, manipulation of the neck can damage the vertebral arteries, which supply blood to the brain. So-called vertebral dissection can ultimately cut off the blood supply, which in turn can lead to a stroke and even death. Because there is usually a delay between the vertebral dissection and the blockage of blood to the brain, the link between chiropractic and strokes went unnoticed for many years. Recently, however, it has been possible to identify cases where spinal manipulation has certainly been the cause of vertebral dissection. (ref)
The BCA did not sue Simon over this, but if you go the the site of the General Chiropractic Council, you find a letter from one of their board members to Dr Miriam Stoppard (who had mentioned this danger in a Daily Mirror article):
There is no evidence that examination or manipulation of the neck causes stroke. Journalists, and a few others, routinely confuse association with cause but as a registered medical practitioner you will be aware of the distinction. (ref)
The bit about confusing association and causality is itself confused. Consistent association between A and B does imply causality - it's just that the causality may be from A to B; from B to A; or from C to both A and B.
Moreover the statement that there is "no evidence" is untrue (see for example: here, here, here, and here - Thanks to @Blue_wode for these!)
Perhaps some pro-chiropractic bloggers might like to demolish these references.
But to come (finally) to the point (and leaving aside the question of who is right and who really has evidence) we have here a strange asymmetry:
Scientist accuses chiropractors of having no evidence and chiropractors sue.
Chiropractor accuses scientist of having no evidence and scientists don't sue.
Perhaps we should ;)
At the very least, we should expose their hypocrisy - which I hope I've just done.