How did local sejmiki gain power as the central Sejm weakened?

As the central Sejm weakened during the 17th century, the Polish-Lithuanian Commonwealth experienced a significant fragmentation of sovereignty. This decline was largely driven by the liberum veto, a practice that allowed a single dissenting deputy to paralyze legislative proceedings by blocking the passage of laws.1

Because the central government lacked a robust bureaucracy and the Sejm became increasingly ineffective, essential state functions—most notably in matters of taxation—shifted to the local sejmiki (regional dietines). This transition occurred because the szlachta (gentry) viewed the sejmiki as the primary protectors of their local interests and liberties, often binding their deputies to strict instructions that prevented compromise at the national level. Consequently, the Commonwealth’s administrative and financial authority became decentralized, leaving the state vulnerable to internal factional strife and external pressures.1