  In this article, we develop an interdisciplinary analysis of MEV which
desires to merge the gap that exists between technical and legal research
supporting policymakers in their regulatory decisions concerning blockchains,
DeFi and associated risks. Consequently, this article is intended for both
technical and legal audiences, and while we abstain from a detailed legal
analysis, we aim to open a policy discussion regarding decentralized governance
design at the block building layer as the place where MEV occurs. Maximal
Extractable Value or MEV has been one of the major concerns in blockchain
designs as it creates a centralizing force which ultimately affects user
transactions. In this article, we dive into the technicality behind MEV, where
we explain the concept behind the novel Proposal Builder Separation design as
an effort by Flashbots to increase decentralization through modularity. We
underline potential vulnerability factors under the PBS design, which open
space for MEV extracting adversarial strategies by inside participants. We
discuss the shift of trust from validators to builders in PoS blockchains such
as Ethereum, acknowledging the impact that the later ones may have on users'
transactions (in terms of front running) and censorship resistance (in terms of
transaction inclusion). We recognize that under PBS, centralized (dominant)
entities such as builders could potentially harm users by extracting MEV via
front running strategies. Finally, we suggest adequate design and policy
measures which could potentially mitigate these negative effects while
protecting blockchain users.
