Margaret Gribbon, who acts for the Professional Footballers' Association (PFA) Scotland, warned that any future independent government would be well advised to stop the charges as soon as possible.
It follows a dramatic 68 per cent drop in the number of cases since the fees were introduced.
Ms Gribbon, of Bridge Litigation Solicitors, said: "The introduction of Employment Tribunal fees has had the impact that many feared it would have; fees are preventing individuals, particularly the most vulnerable, from accessing justice in the employment tribunals after being unfairly dismissed, discriminated against or underpaid by an employer.
"The staggering reduction in the number of claims lodged since the introduction of fees demonstrates, beyond doubt, that only those who can afford it are able to seek redress following unlawful treatment at work. Fees are unfair and unjust and their retention, in any form, is extremely difficult to justify.
"It is a very unpopular decision and - should there be a Yes vote in September - any future independent Scottish Government would be wise to ditch the fees as soon as possible."
Figures obtained under freedom of information laws show there have been almost 5000 fewer cases in the nine months after the fees were introduced on July 29, compared with the same nine months the previous year.
Scotland has experienced an above-average drop - statistics showed that UK-wide claims had fallen by 59 per cent for the three months from January to March this year.
The Scottish Government opposed the fees and during a recent discussion in Parliament on the issue, Roseanna Cunningham, minister for Community Safety and Legal Affairs, said that "principled opposition" would continue if a Yes vote is achieved.
But the Conservatives said the figures should be welcomed. Tory chief whip John Lamont said: "You'd think a drop in employment tribunals would be something to welcome, not gnash teeth over."