We propose an extension to Einstein-Cartan theory by promoting the spin contribution to torsion to a dynamical quantity with a characteristic relaxation time. We introduce a new constant, the Duenas Constant λ_D, coupling the time derivative of the spin tensor to the Ricci curvature. The resulting field equations reduce to EC for λ_B=0 or for spin flips with duration τ→∞. For rapid spin flips, curvature is amplified by a factor η_D = 1 + λ_D/8πGτ^4. We prove the enhancement factor is well-defined for all τ>0, λ_D≥0, and derive current experimental bounds λ_D ≲ 10^-44 s^4/kg⋅m from torsion pendulum data. For λ_D near this bound, picosecond spin flips predict η_D∼10^14. We outline tabletop tests using pulsed magnetic fields on polarized ensembles. DSCG is falsifiable via its unique τ^-4 scaling.