The power of attorney should state clearly that it will take effect
at a specific time or when a specific event occurs. This would include
the mental incapacity or infirmity of the maker of the document
(donor). The document can then go on to specify when and how it
will be determined that the event has occurred.
In the case of the mental incapacity or infirmity of the donor
of the power, the document could provide that it would be determined
when one or more named persons have made a written declaration to
that effect, for example, two doctors. The document should name
someone to be the person who will make the determination based on
the written declaration from the doctors.