Spectrum efficiency is an important pillar of spectrum management given the rapid growth in the needs for more spectrum. It is an ideal topic for expert discussion, and it is an excellent graduate school research topic. Spectrum efficiency can be quite controversial at times when major spectrum-using entities disagree on the definition, metrics, and service rules for spectrum usage. TPRC has convened a panel of spectrum management experts to cover current controversies or high-profile developments associated with improvements or new policies seeking to achieve more efficient use of increasingly scarce spectrum. Panelist will provide updates on these issues along with their view of current knowledge gaps where further research is needed to better understand how to address these challenges.