The committee has rejected proposals in the Local Government and Health Involvement Bill which would mean consultation would only have to be done on 'significant' rather than all proposals and decisions.
The bill defines 'significant' as having substantial impact on the manner in which services are delivered to users or the range of services available to those users.
The report states that in theory, section 11 consultations are an excellent system but in practice there is disquiet, 'people feel they are consulted after decisions have been made'.
'There has also been criticism of NHS organisations' refusal to consult about major changes and of the Department of Health's vigorous support of these decisions,' the report says. 'We fear the bill will weaken section 11. The change of definition it proposes may lead to confusion and could lead to more court cases when the act is tested.'
NHS Confederation policy manager Maria Nyberg said the committee's conclusions on the bill were worrying. 'We do not believe that the legislation will weaken consultation. Rather, we need to be clear about the difference between ongoing patient and public involvement in decision-making, and formal consultations on significant service redesign.
'Ongoing involvement and engagement with patients and the public about health is of course essential if healthcare is truly going to be patient focused. Engaging with the local population must be properly embedded within NHS organisations.
'However, involvement is very different from formal public consultation, which is not required unless significant changes are being made to service quality, quantity or access.'
She added: 'Healthcare providers and commissioners need to be able to make clinical and managerial decisions quickly and remain agile in a competitive market.'