A proposed reform of mental health laws could lead to people with only mild conditions being locked up and forcibly treated, MPs and peers have warned.
MPs and peers believe the law could be used as a form of social control
The joint House of Commons and House of Lords Committee said the draft Mental Health Bill made it too easy to force a person into compulsory treatment.
Current laws do not allow people with severe personality disorders who have committed no offence to be detained.
But the committee warned the Bill could be used as a "social control".
Ministers said the report's recommendations would be considered.
Committee chairman Lord Carlile of Berriew said the bill was "fundamentally flawed".
"It is too heavily focused on compulsion and currently there are neither the financial resources nor the workforce to implement it."
Former Home Secretary Jack Straw believed the loophole which means people with severe personality disorders led to the release of Michael Stone before he killed Lin Russell and her daughter in a hammer attack in Kent in 1996.
The original 2002 draft bill proposed measures to detain mentally ill patients for their own protection and the protection of others, even if their condition was not treatable.
There were also proposals to allow compulsory treatment in the community under community treatment orders.
When it was published, an unprecedented 2,000 objections were made.
Last autumn, a revised draft was published which tightened the definition of those the laws could apply to.
But the committee said it feared the bill as it now stands could be used as a mental health anti-social behaviour order, or Asbo, - enforcing treatment on those who might be a nuisance, but do not actually pose a real threat.
The bill says treatment can be enforced "for the protection of other persons".
But the committee said this should be changed to cover people who "pose a significant risk of serious harm".
It also said patients should never be treated under compulsion unless their decision making was impaired and the treatment was of therapeutic benefit.
The wide definition of treatment at the moment meant people diagnosed with personality disorder or learning difficulties could be detained on the grounds of safety rather than benefit to their health.
Paul Farmer, the chairman of the Mental Health Alliance, which represents the 50 largest mental health groups, said the government should withdraw the current bill and draw up a new version based on the committee's recommendations.
"The committee has clearly listened to service users, carers, professionals and charities."
Sophie Corlett, director of policy at mental health charity Mind, said the report was a "clear wake-up call" for the bill's supporters.
Sane chief executive Marjorie Wallace said: "Changing the law alone will not work unless we ensure proper care and treatment, which are still so often lacking."
And Dr Tony Zigmond, vice president of the Royal College of Psychiatrists, added the draft bill would have undermined the trusts between patient, carer and psychiatrist.
"The committee's recommendations, if adopted by government, would ensure an ethical and practical framework for mental health legislation."
A Department of Health spokeswoman said: "We have received the report and will be reading it carefully. We will be publishing a full response in due course."