Bad bosses are getting away with discrimination and unfair treatment because employees are being "priced out of justice" by tribunal fees, the TUC has claimed.
Figures published by the trade union body show that the number of people pursuing a tribunal case has fallen by 9,000 a month since charges of up to £1,200 were introduced in 2013-14. Workers have to pay the fee if a member of their household has savings worth £3,000 or more.
The TUC said that between 2012-13 and 2015-16, there was a 73 per cent drop in unfair dismissal claims, along with sharp falls in challenges over discrimination on the grounds of sex (down 71 per cent), race (down 58 per cent) and disability (down 54 per cent).
Ministers argued the fees would stop vexatious claims and promote alternative means of solving workplace disputes.
The TUC is calling on the Government to urgently publish a review of the impact of tribunal fees that the Ministry of Justice was supposed to have issued by the end of 2015.
It is also urging Chancellor Philip Hammond to abolish the fees in the Autumn Statement.
However, the Ministry of Justice said it is "right that those who use our tribunals should contribute to the £71m cost of running the service".
Frances O'Grady, TUC general secretary, said: "These figures show a huge drop in workers seeking justice when they've been unfairly treated. Now bosses know they can get away with it, discrimination at work can flourish unchecked and people can be sacked without good reason.
"The evidence is there for all to see. These fees - of up to £1,200, even if you're on the minimum wage - are pricing out thousands each month from pursuing cases.
"Theresa May has repeatedly said she wants to govern for ordinary working people. Here is a perfect opportunity. She could reverse employment tribunal fees, and make sure workers can challenge bad employers in court."