It pledges to table a libel reform bill should it win next month's general election.
Dominic Grieve QC, the shadow justice secretary, made the commitment to a reform bill just days after the move to curb the success fees charged by defamation lawyers was stopped in the House of Commons.
Grieve said: "The Conservative party is committed, if elected, to undertaking a fundamental review of the libel laws with a view to enacting legislation to reform them.
"This reform could best be done by means of a separate libel bill and this is the preferred approach for us."
All three of the major political parties have now made similar commitments to reform the libel laws.
Justice secretary Jack Straw, a long-term advocate of libel reform and a specific bill to push new laws through parliament, was joined by Nick Clegg, leader of the Liberal Democrats, who made a commitment to libel law reform in a speech to the Royal Society in March.
The move by Grieve was welcomed by the Libel Reform Campaign, a coalition of organisations led by English PEN, Index on Censorship and Sense About Science.
John Kampfner, chief executive of Index on Censorship, said: "After the long-awaited cut to lawyers' fees was blocked in the House of Commons this week, we're delighted by this good news from the Conservative Party.
"Now, all three major political parties are committed to a Libel Reform Bill in the next Parliament."
Oliver Luft writes for Press Gazette.