Critics of Pope John Paul's system said that instead of simply avoiding a deadlock, the changes he made in 1996 could in theory empower any majority willing to hold out until the two-thirds requirement expired.

BBC: Pope Benedict (file image)

Under a complex system of legislative and religious checks and balances, deadlock between parliament and the Guardian Council is dealt with by the Expediency Council, at present chaired by Mr Rafsanjani.

ECONOMIST: Iran

The American political system works well when the conclusion of heated debate is compromise, not deadlock.

FORBES: Obama: The Federal Government Will Be Open For Business

One of the sticking points that caused the Senate to deadlock on rewriting America's immigration laws was a proposed point system for allocating visas.

NPR: Critics Dispute Effects of Immigration Point System