Cuts to legal aid have created a two-tier justice system in "crisis", a new report warns.
The Bach Commission on access to justice has called for a set of minimum standards to be introduced to ensure legal representation for all.
Poor people are being left without advice or professional support due to the impact of cuts, the interim report released by the Fabian Society finds.
Chairman of the commission, Labour peer Lord Bach, said: "Our interim report shows that our justice system is creaking at the seams. The Legal Aid Sentencing and Punishment of Offenders Act cuts have produced a crisis in the justice system and the poorest in our society can no longer receive the legal support they require.
"This unacceptable state of affairs needs challenging and changing. This report is the starting point in our ongoing work to redesign the justice system so that it works for all. The commission intends now to turn to working through the policy solutions to fix this crisis."
The report finds that those "most in need" have been left without legal help because changes to eligibility rules mean most cases involving housing, welfare, debt, immigration, medical negligence and family law no longer qualify.
The probe says the Exceptional Case Funding (ECF) scheme, which was meant to offset the impact of cuts, has failed to deliver due to "extremely low levels of take-up".
"The Government suggested around 847 children and 4,888 young adults would be granted ECF each year. Yet between October 2013 and June 2015 only eight children and 28 young adults were granted legal aid under the scheme."
With the number of not-for-profit legal advice centres falling from some 3,226 in 2005 to 1,462 in 2015, access to legal help and education has become "inadequate and disjointed", the study warns.
Lord Bach's commission also found that the introduction of employment tribunal fees saw the number of single cases fall dramatically, with a slump of 67% between October 2013 and June 2014.
The report expresses concern at the levels of bureaucracy in the Legal Aid Agency, where it says the administration budget increased last year by £2.1 million, despite overall cuts of 25%
Britain is also lagging behind in implementing new technology systems, the report says
The commission called for reducing restrictions on claiming legal aid and the introduction of a set of minimum standards for access to justice in England and Wales, overseen by an independent body.
Lord Bach was originally asked to undertake a review of the legal aid system by Labour leader Jeremy Corbyn last autumn, but the peer says he then decided to establish a commission of independent experts to drive a wider investigation of access to justice.
Labour's shadow justice secretary Richard Burgon said: "Since 2010, the Conservatives have implemented unprecedented cuts to legal aid - putting justice beyond the reach of thousands. There is much of substance in the report, which will be welcome to all those who value the principle of access to justice.
"I am particularly excited by the idea of enshrining in law a minimum standard for access to justice. A basic threshold for access to justice has the potential to be a historic advance in our law which could improve the lives of thousands."
A Ministry of Justice spokesman said: "We have a world-leading legal system and last year spent more than £1.5 billion on legal aid.
"We must ensure legal aid is sustainable and fair - both for those who need it and the taxpayer who pays for it. That is why we have made sure support remains available to the most vulnerable and in the most serious cases.
"We have committed to carrying out a post-implementation review of the civil legal aid changes and an announcement on this will be made in due course."