In the past month, Lewisham and Warwickshire have announced plans to scrap their Connexions services before alternative provision is in place, with several other local authorities expected to follow suit.
One of the options being considered by the councils is using schools and colleges to provide careers advice to young people and then purchasing additional services from external providers.
Denise Bertuchi, assistant national officer for education and children's services at Unison, said: "The Education Bill states clearly that local authorities are obliged to provide impartial and professional careers advice to young people," she said. "If there's sufficient evidence to show this isn't happening, we're investigating the possibility of a judicial review this summer."
Unison estimates that 8,000 Connexions jobs are at risk as a result of local authority cuts.
Connexions staff in Lewisham were told last month that the service would close from 18 March with 35 staff facing redundancy.
In Warwickshire, the council is planning to cut 80 per cent of its Connexions budget from March and no longer provide dedicated careers advice services to young people.
Josh Harsant, 17, a trustee of Connexions Thames Valley who has been leading a national campaign to ensure young people receive high-quality information, advice and guidance (IAG), said: "Teachers and youth workers are not a suitable replacement for personal advisers with years of experience of providing impartial and unbiased advice to young people."
A spokesman for Lewisham said: "Funds which were provided to the council for careers advice have been significantly reduced. The council will need to focus its available resources on the most vulnerable young people."
Meanwhile, a spokesman for Warwickshire said: "Decisions about the level of information, advice and guidance that is required will be taken as part of the council's budget setting in February."
