In July last year, the UK ISPs called for the High Court to launch the review, stating the Act was "rushed through" and had "insufficient scrutiny".
The Digital Economy Act, which covers a number of issues including measures designed to tackle internet piracy, became law in April last year. Under its net piracy measures, copyright holders will collect IP addresses of web users thought to have illegally downloaded material. The details will then be passed to ISPs, who will be responsible for issuing warning letters and emails.
This 'mass notification system' will be trialled for a year. If it does not reduce illegal file-sharing by 70 percent, then web users thought to have illegally downloaded will face 'technical measures' such as being suspended from the web temporarily.
TalkTalk and BT believe these plans could be in breach of "basic rights and freedoms". If the challenge is given the go-ahead by the High Court, a decision which is expected by the end of the week, the review process will then begin. However, this could last until spring 2012, delaying the implementation of the measures even further. Initially, they had been expected to be rolled-out at the beginning of this year.
"Since the DEA passed into law there has been a considerable amount of work to do to implement the mass notification system," said the Department for Culture, Media and Sport.
"Secondary legislation setting out how the system will be paid for and how it will work has to be passed by parliament. Ofcom also has to set up an appeals process."
Last month, Culture secretary Jeremy Hunt instructed Ofcom to investigate whether ISPs can be forced to block websites that host copyright-infringing content. The regulator is expected to offer its verdict on the measure in the summer.