Last-minute changes to the Digital Economy Bill due to become law before the general election mean that cafés, pubs and airports offering Wi-Fi could be prosecuted if customers view, download or share copyright-infringing material while on their premises.
The amendments, already passed by the House of Lords and due to go before the Commons this summer, are part of the wider Bill aimed at stopping websites from illegally showing copyright-infringing material, such as football highlights, film clips or music videos.
But coffee shop chains are concerned that the proposals to include shop owners have gone too far. Maggie Wright, spokeswoman for Coffee Republic, which has sites with Wi-Fi access across the UK, said: "We have looked at the contents of this Bill and are extremely concerned by some of the proposals."
Meanwhile, Clare Sheppard, spokeswoman for bakery chain Le Pain Quotidien, which has more than a dozen outlets with Wi-Fi across London, added: "The proposals seem to be unfair and unworkable."
Lord Clement-Jones, the Liberal Democrat peer who tabled the amendment, said the changes would offer a "more proportionate, specific and appropriate" way to tackle copyright infringement.