A report found receptionists carried out initial checks on patients
A solicitor representing campaigners has condemned a second inquiry into failings at Stafford Hospital as "a narrow, private process".
Richard Stein, who is acting for the Cure the NHS (CtN) group, was speaking on the opening day of the inquiry.
He said many relatives felt other reports had already established what happened to patients.
In March, a Healthcare Commission report said "appalling" emergency care had led to patients "dying needlessly".
It also condemned the local NHS trust for allowing unqualified staff to carry out checks on patients.
CtN held a silent protest after a meeting on Tuesday.
Mr Stein said CtN now intended to seek a judicial review of the limited scope of the independent inquiry.
"It's extremely disappointing for patients and for bereaved relatives that it's going to be a narrow, private process rather than the open, public and all-embracing one that the people of Stafford need and deserve," he said.
Speaking after inquiry chairman, Robert Francis QC, had outlined the terms of reference, CtN founder Julie Bailey described its scope as a "whitewash" which would not establish what went wrong.
After meeting with interested parties, Mr Francis promised it would allow patients and their families to give an account of their experiences.
He confirmed oral hearings, including those involving staff and senior managers at the hospital, would be held in private.
Asked why the inquiry would be held in private, Mr Francis pointed out much of the material he would have to consider would be sensitive and confidential medical information.
Mr Francis said: "I drew to the secretary of state's attention [to the] view of mine and also the request by Cure the NHS that the terms of reference should be extended.
"He wrote to me recently... declining in that respect to extend the terms of reference."
The report in March said about 400 more people died at the hospital between 2005 and 2008 than would be expected.
It also found receptionists carried out initial checks on patients.
The Care Quality Commission, which replaced the Health Commission, said there had been progress, but some areas had to be addressed "urgently".
The trust has said lessons had been learned and staffing levels had been increased.