Full Idea
Libet himself points out that the conscious decisions still have the power to 'endorse' or 'cancel', so to speak, the processes initiated by the earlier cortical activity: no action will result if the action's execution is consciously countermanded.
Gist of Idea
Libet says the processes initiated in the cortex can still be consciously changed
Source
report of Benjamin Libet (Unconscious Cerebral Initiative [1985]) by David Papineau - Thinking about Consciousness 1.4
Book Reference
Papineau,David: 'Thinking about Consciousness' [OUP 2004], p.24
A Reaction
This is why Libet's findings do not imply 'epiphenomenalism'. It seems that part of a decisive action is non-conscious, undermining the all-or-nothing view of consciousness. Searle tries to smuggle in free will at this point (Idea 3817).
Related Idea
Idea 3817 Free will is most obvious when we choose between several reasons for an action [Searle]