This means GPs in Britain will inform employers of tasks employees would be able to perform at work, rather than signing them off work with a sick note.
But according to Thompsons Solicitors, if employers are not prepared to make changes to working conditions for staff returning after illness or injury - such as adapting work stations or duties - then staff will be unable to return to work, or will return only to go off sick again.
The firm also believes the reforms will fail to cut the cost of sick leave or reduce compensation payments on employees made ill or injured because of their employer's lack of action.
Tom Jones, head of policy at Thompsons, said: "We support reform of the system in principle. It is always better to find ways of helping people back to work after injury or illness than having them off sick.
"However, many people remain on sick leave because employers fail to make the necessary adjustments to enable them to work again. This voluntary approach is highly unlikely to change that. People often find themselves in a no man's land: not wanting to stay off work, but unable to return.
"Under the proposals employers might take someone back before they are ready, and even coerce them to do so and then dismiss them when they cannot cope. This is neither in the employee's nor the employer's interest.
"The proposed system would do nothing to tackle the issue of long-term health and well-being. The Government's new work-health strategy must focus on the employer's duty to help people back to work. As with rehabilitation, it cannot be used as a stick with which to beat the sick and injured. Hard-working families who have lost income through no fault of their own must not be further punished."