India, April 27 -- The decision by Raghav Chadha and six other Rajya Sabha MPs to break away from the Aam Aadmi Party (AAP) and announce a "merger" with the Bharatiya Janata Party (BJP) has triggered one of the most consequential constitutional questions on defection law in recent years. While the rebels claim protection under Paragraph 4 of the Tenth Schedule, which provides immunity in cases of "merger" supported by two-thirds of a legislature party, the legal position is far from settled.

At the heart of the controversy is a deeper constitutional tension: can a group of legislators, by virtue of numerical strength alone, claim a valid merger without a corresponding decision by the "original political party"? The answer will determine ...