A new report from the Oireachtas Committee on European Affairs claims ratification of the Lisbon Treaty will enhance workers' rights and strengthen their entitlement to collective bargaining, including strike action.
It also rejects claims the Treaty will undermine employees' pay and working conditions.
Co-author of the report Labour TD Joe Costello said: "The charter of fundamental rights is very strong on workers rights. In fact for the very first time there is reference in European treaties to a commitment to collective bargaining.
"That's going to be law if the Lisbon Treaty is passed; it will not be law if the Lisbon Treaty is not passed."
Sinn Féin President Gerry Adams claims, however, that a new Lisbon Treaty is needed to underpin workers' rights.
Mr Adams believes a new treaty is also needed to protect public services, promote democracy and defend Irish neutrality,
"If you don't believe in workers' rights, if you don't believe in public services. if you believe in NAMA, if you believe in two-tierism, then of course you'll vote the other way. But if you believe in those as core principles then I believe people will vote no."