When a person loses mental capacity to make decisions for themselves and they do not have a power of attorney in place, then the Court of Protection will need to appoint a deputy to make decisions for that person.
A Lasting Power of Attorney is something that a person can put in place when they have mental capacity (the ability to make their own decisions) in order to appoint someone to help make decisions for them, particularly in the future if they are no longer able to do it for themselves.
A deputyship is awarded by the Court of Protection where someone applies to help make decisions for someone who is unable to make decisions for themselves. This may be due to something temporary, such as a coma, or long term, such as a serious brain injury.