In order to implement a voting system based on blockchain technology, there are various legal obligations and requirements that must be fulfilled to ensure security, privacy, and accessibility. 

First, the system must comply with election laws such as the Help America Vote Act (HAVA) and National Voter Registration Act (NVRA) in the United States, which relate to voter accessibility and election security. The voting system must also meet privacy requirements, including protecting voter privacy under laws such as the General Data Protection Regulation (GDPR) in the European Union and the California Consumer Privacy Act (CCPA) in the state of California. 

Another important legal requirement is accessibility, which provides eligible voters, especially those with disabled users, the ability to use the voting system, as required under HAVA. Similarly, security is of utmost importance for a voting system, and the system must be resistant to attempts at cyberattacks and election fraud by following best practices determined by organizations like the National Institute of Standards and Technology (NIST). 

Furthermore, blockchain-based voting systems must have transparency and auditability as part of its operational framework by requiring publicly accessible records of transactions, along with a verifiable ledger system to support recounting and election verification capabilities. The voting system must comply with laws relating to voter eligibility and election processes in each jurisdiction in which it is implemented and must meet basic national and international standards such as the Election Assistance Commission (EAC). 

Finally, any liability or legal accountability must be clear and defined for any legal repercussions that may occur in a blockchain-based voting system.