Taiwan's government and opposition-controlled legislature are heading into a showdown over a special bill to buy home-built military drones, with the cabinet warning that lawmakers are overstepping their constitutional role.

• Talks between the parties broke down, so the drone procurement bill goes to a floor vote on the last day of the legislative session.
• Premier Cho Jung-tai insists the defense ministry, not commercial interests, must lead the program.
• The cabinet's main complaint is lawmakers writing spending into the text of a law, which it says the constitution does not allow.
• Similar fights have flared repeatedly over the past two years, straining relations between the executive and the legislature.
• A related worry: packing multiple questions onto a single referendum ballot would make voting and counting far harder to run.

Outlook: The vote will decide whether Taiwan's drone buildup moves ahead on the government's terms or on the legislature's, and either way the constitutional dispute between the two branches looks set to continue.