There is no law behind PBNYC. It exists because individual Council Members choose each year to let residents decide at least $1 million of the capital discretionary funds the Speaker allocates to them, and because, since 2014, successive Speakers' offices (Mark-Viverito, Johnson, Adams, Menin) have chosen to fund central coordination. The mandate is a published rulebook, revised annually, that member offices sign onto; the Cycle 2 rulebook calls itself 'a work in progress'. The voluntary character shows in the numbers: participation rose from 4 districts to 32 in Cycle 8, fell to 27 in Cycle 7, 29 in 2023, 25 in 2025 and 22 in 2026 as members opted in or out, and the 2023 release describes that year's vote as the first 'since the start of the pandemic'. Bindingness is by pledge: the rulebook commits members to 'submit winning projects to be allocated in the City's upcoming fiscal year budget', members resolve ties, and the evaluators found every cycle's winners funded, often with extra money for non-winning projects. The pledge still passes through gates outside the process: the City budget adopted in June, agency feasibility vetting during proposal development, and agency implementation afterwards. Scope is full discretion within capital eligibility rules, with documented exceptions: District 5 in Cycle 3 voted on a ballot of pre-approved, not yet funded projects because its new member took office after the assembly phase; Cycles 3 and 6 allowed some districts to add expense funds, and Districts 39 (2019) and 2 (2026) ran expense pilots. Political shifts mattered: PB was a 2013 Council campaign issue, 21 new members were elected, the pilot member Melissa Mark-Viverito became Speaker and committed central resources, and a May 2014 rules reform replaced Speaker-preference distribution of discretionary funds with a public formula.