We report individual dynamical masses for the brown dwarfs \varepsilon Indi B and C , which have spectral types of T1.5 and T6 , respectively , measured from astrometric orbit mapping . Our measurements are based on a joint analysis of astrometric data from the Carnegie Astrometric Planet Search and the Cerro Tololo Inter-American Observatory Parallax Investigation as well as archival high resolution imaging , and use a Markov Chain Monte Carlo method . We find dynamical masses of 75.0 \pm 0.82 M _ { Jup } for the T1.5 B component and 70.1 \pm 0.68 M _ { Jup } for the T6 C component . These masses are surprisingly high for substellar objects and challenge our understanding of substellar structure and evolution . We discuss several evolutionary scenarios proposed in the literature and find that while none of them can provide conclusive explanations for the high substellar masses , evolutionary models incorporating lower atmospheric opacities come closer to approximating our results . We discuss the details of our astrometric model , its algorithm implementation , and how we determine parameter values via Markov Chain Monte Carlo Bayesian inference .