"Unanimous" opposition to the federal government's proposed copyright law changes will force it back to the drawing board to tackle online piracy, Communications Minister Malcolm Turnbull says.

Representatives from both sides of the online piracy debate - including the telecommunications companies and rights holders - have warned the changes to copyright law outlined in the government's discussion paper on online piracy are too broad and could have negative unintended consequences.

Mr Turnbull hosted a lively public forum in Sydney on Tuesday night that included panellists from the film and television sectors, internet service providers and consumer groups.

The government has proposed creating a new legal framework - known as "extended authorisation liability" - to make internet service providers more accountable for their customers' illicit downloading.