A valid consent has five moving parts: capacity, disclosure, understanding, voluntariness and authorisation. Choose one move for each part and watch the encounter hold together or quietly fall apart. The form gets signed either way — that is the point.
Where is this happening?
The three exceptions — and how narrow they are
What a signature is worth
In litigation the form establishes only that a consent process was claimed; the fight then moves to whether the disclosure was adequate. Courts have found consent invalid despite a signature and valid without one. What protects patients — and incidentally clinicians — is a contemporaneous note of what was discussed, in what words, with whom present.