Tens of thousands of the poorest and most vulnerable in society are being denied access to justice as a result of the Government's cuts to civil legal aid, Amnesty International has warned.
Changes to the legal aid rules in England and Wales were creating a "two-tier justice system" open only to those who could afford to pay, a report by the human rights organisation concluded.
When the Legal Aid, Sentencing and Punishment of Offenders (LASPO) Act came into force in 2013, there was a "staggering" fall-off in the number of civil cases where legal aid was granted - from 925,000 the previous year to 497,000, the report said.
Amnesty called on ministers to launch an immediate review of a system which it said had clearly been shown to be failing.
Researcher Alice Wyss said: "Cuts to legal aid imposed by this Government have decimated access to justice and left thousands of the most vulnerable without essential legal advice and support.
"We are in danger of creating a two-tier civil justice system, open to those who can afford it, but increasingly closed to the poorest and most in need of its protection.
"If Theresa May is really determined to deliver a country that works for all then there needs to be a justice system for everyone, not just those who can afford it."
The report warned that since the legislation came into force, "advice deserts" had emerged across parts of the country - particularly in the South West, the Midlands and parts of the North of England - where access to free legal advice was disappearing altogether.
At the same time, it said that a "safety net" scheme - known as exceptional case funding - intended to ensure the rights of the vulnerable and disadvantaged were protected had "systemic and inherent failings" and was not working.
Among those hardest hit by the changes, the report warned, were children and vulnerable young people.
"Children and vulnerable young people cannot be expected to navigate complex legal processes alone, yet that is precisely what LASPO allows for. The impact has also been felt in cases where the best interests of the child are very much at stake," the report said.
Other groups adversely affected included migrants and refugees and people with additional vulnerabilities such as mental health problems, learning disabilities and drug or alcohol dependency.
"In human rights terms, the cuts to legal aid constitute a retrogressive measure," the report said.
"They were primarily motivated by a desire to reduce spending on the justice system at a time of increased fiscal pressure, but were made with insufficient regard for the potential negative and profound impacts on the protection of human rights in the UK.
"There is no dispute that fewer people can now access free legal help and representation in a wide range of cases."