Once the LPA has been drawn up it has to be registered with the Office of the Public Guardian (OPG) before it can be used by your attorney. Once registered the LPA can be used by your attorney, even if you still have mental capacity to deal with your affairs. Early registration is, nevertheless, recommended as the OPG can reject LPAs for a variety of reasons. Once rejected, the LPA is regarded as invalid.An LPA can only be made if the donor has the mental capacity to do so. Once capacity has been lost, an application to the Court of Protection is required to approve a deputy to deal with a person’s financial affairs. This is a much more lengthy and expensive process.An attorney has to act in your best interests at all times and can only make a decision on your behalf if he has a reasonable belief that you have lost the mental capacity to make that particular decision.