History
Veto Player Theory and Legislative Gridlock
Quick fact
In the U.S., the combination of a bicameral legislature, a presidential veto, and the need for supermajorities in the Senate means that as few as 41 senators can effectively block most legislation—creating the famous '60-vote' threshold for major bills.
Why this is interesting
Why do some governments pass dozens of major laws in a year, while others struggle to change even minor rules? The answer often lies not in the leaders, but in how many people have the power to say 'no.'