Who defines what constitutes "consent"?

If a family all convince Grandma that she'd be better off dead so that they split up and enjoy her estate, did she "consent" or was she coerced under duress?

If the ACA redirects resources from palative care to HIV/AIDS treatment, and the elderly who would likely make use of palative care are communicated to and understand that the palative care is under staffed, under resourced and generally untenable are the willingly consenting or are they being courted by pro euthanasia proponents with a financial interest in hurrying along their timely demise?

In the Netherlands dementia and Alzheimer patients are allowed to "consent" despite their have already been determined to be mentally incompetent!

If you look at only the existing real world data it suggests very, very clearly that the original "patients rights" rational is only the nose of a very very dangerous camel being let into the tent.