Making Policy in Parliamentary and Presidential Systems

In a fused parliamentary system like Britain's, the prime minister and cabinet sit inside parliament and usually command a disciplined majority. A bill introduced by the government is really the majority's own agenda, so it clears first reading, committee, second and third readings, and royal assent with few real obstacles. The governing party controls the floor, the timetable, and the vote. Because the executive's survival depends on that same majority, backbenchers rarely defect, so there is essentially one veto point: the governing coalition itself.

In a separated presidential system like Mexico's, the president is elected independently of Congress and cannot be removed by a no-confidence vote, and Congress cannot be dissolved by the president. A bill must survive separate approval in the legislature, often bicameral, and then survive a presidential signature or veto, and sometimes a court challenge after that. If the opposition controls Congress, as in divided government, the president has no built-in majority to rely on, so each stage becomes an independent veto point where the bill can stall, be amended, or die. Semi-presidential systems split the difference: a directly elected president shares executive power with a prime minister who still needs parliamentary confidence, adding a third pattern of veto points.

Coalition governments complicate the simple fused-system story. A prime minister who depends on a coalition partner to hold a majority must negotiate with that partner before legislation reaches the floor, which adds a veto point inside what looks like a single fused system and slows things down, though usually not as much as full separation does.