All you need to know about the Irish vote on the Lisbon Treaty.

What happens now that Ireland has said "no"?

All 27 EU member states have to ratify the treaty, so at the very least it is unlikely that it will come into force by the scheduled date of January 2009. The Irish result could see the treaty scrapped altogether. However, France - which takes over the EU presidency next month - argues that an Irish "no" should not block ratification.

Can the Irish result be overturned by calling another referendum?

In 2001, the Irish rejected the Treaty of Nice. The following year another vote was held, which was won by the "yes" camp.

Why did Ireland vote no?

The political parties were outfought by a professional "no" campaign led by Declan Ganley, a multi-millionaire businessman. His camp argued that Ireland's voice would be weakened in Europe. Other issues included fears that Ireland would be harmed by EU tax harmonisation and would lose out in world trade talks. They have also raised fears that its traditional positions on abortion and neutrality will be undermined.

What would be the effect of the treaty?

Instead of universal unanimity, more policy areas will be governed by a double majority voting system, notably in justice and home affairs. A long-term European Council would be created instead of the current six-month rotation between member states.

The European Commission would be downsized, with the executive body comprising commissioners from two-thirds of the member states. A new post of EU foreign policy chief would be created.