EU leaders have agreed a deal they hope will secure the Lisbon Treaty a "Yes" vote in a second Irish referendum.
Ireland won legally-binding assurances that Lisbon would not affect Irish policies on military neutrality, taxes and abortion, diplomats said.
French President Nicolas Sarkozy said leaders had agreed to Irish demands that the guarantees would be given the status of a treaty "protocol".
But he stressed it would not affect the other 26 member countries.
The leaders have also agreed in principle to a new framework of rules to oversee the EU's financial sector.
On Thursday they backed Jose Manuel Barroso for a new term as president of the European Commission.