He said that specialist schools which select by aptitude choose parents rather than pupils. "At least in theory the 11-plus is neutral and bureaucratic, you pass or fail the test. Aptitude selection is wholly a matter of judgment," the former health secretary said.
Mr Dobson was speaking at the launch of a campaign to try to persuade the Labour leadership to abolish grammar schools.
He is one of 150 leading Labour figures, including MPs, trade unionists and local government leaders, who have written to party members asking them to lobby the leadership over ending selection.
The Government has introduced ballots to allow parents to abolish selection where a majority wish it. Opponents of the 11-plus complain that the rules are rigged against them and that the process is bureaucratic, arbitrary and expensive.
Research, carried out by the National Foundation for Educational Research, shows that the brightest pupils do better in comprehensives than in grammars. This was presented on Wednesday, in the first of a series of debates on the future of comprehensive schooling hosted by Oxford University.
However, secondary league tables published this week show that pupils in grammar schools improve faster than those in either secondary moderns or comprehensives between the ages of 11 and 14.
Education Secretary Charles Clarke has recently reopened the debate. He has promised to look at the impact of selection on academic performance and last week the Office for Standards in Education produced a special report on selection in Kent at his request.
Giving evidence to MPs on diversity in secondary education, Sir Cyril Taylor, chairman of the Technology Colleges Trust, defended specialist schools.
He said that last summer 54 per cent of pupils in the 650 non-selective specialist schools gained five or more A*-C grade GCSEs compared to 47 per cent in comprehensives and secondary moderns.
But John Dunford, general secretary of the Secondary Heads Association, said specialist schools were increasing divisions in some areas.
League tables, 20-21