A new watchdog for England and Wales has been launched to look after the affairs of people who lack the mental capacity to make their own decisions.
People with mental illness will be protected, the justice minister said
The Office of Public Guardian aims to protect vulnerable people by making sure financial decisions are being made in their best interests.
The organisation will monitor the actions of carers and legal guardians of people with mental illness.
It takes over from the Public Guardianship Office, created in 2001.
Powers of attorney
The new body, introduced under the Mental Capacity Act 2005 and which will begin work from Monday, will be supported by a new Court of Protection, which will settle any disputes concerning those with mental illness.
The current Enduring Powers of Attorney will also be replaced by a Lasting Power of Attorney, which will allow people to choose someone they trust to look after their affairs if required in the future.
Justice minister Bridget Prentice said the measures would bring "legal certainty" to some of the most vulnerable people in society.
Most people would confront mental incapacity during their lives, either themselves or through a member of family, she said.
"This is to give people the opportunity now, that they really haven't had before, to make advanced decisions about how they want their affairs looked after should that happen to them."
She added: "[The] bottom line is that your personal interests have to be protected and everyone else who is involved in trying to help you do that must be doing that in order to ensure that your personal interests are protected."
The first Public Guardian, Richard Brook, a former chief executive of the mental health charity Mind, described the launch of the new body as "a significant step forward" in safeguarding the interests of vulnerable people.
Neil Hunt, chief executive of the Alzheimer's Society, also welcomed the new measures, saying they would allow people to make better choices and have more control over their lives.
"This is a huge step forward and a pivotal moment in recognising the rights of people with dementia," he said.
"Everyone should have plans for the future and we hope thousands of families and loved ones will use the changes as motivation to start planning ahead."
The Office of the Public Guardian will be an executive agency of the Ministry of Justice.
The changes to powers of attorney under the Mental Capacity Act 2005 will not affect the terms of the Adults with Incapacity (Scotland) Act 2000.