Blinding is an issue in trials, because without it it can introduce bias which may over estimate the effect of the drug. This study looked at sativex a cannabis spray and suggests that in trials where the aim was "not to get high" there was nomuch unblinding. The cynic says if you you do not know you are taking it are you taking enough for optimum benefit because the side effect ad effect are controlled by the same things in different parts of the CNS. However even if unblinded it did not make a difference.
Will being unblinded have an influence on the regulators, we shall see the Lemtrada trials were not blinded and so subject to bias, because you knew if you were getting an i.v dose or were injecting yourself (beta interferon). In some other trials the companies have gone to much greater lengths to get class I evidence and have given fake infusions and repeated injections with fake interferon. The people on these trials are doing a heroic job.