Laboratory spectral recordings and accurate molecular spectral analysis of any potential interstellar molecule are essential to generate a complete spectroscopic line list. This permits the prediction of the frequencies and intensities of any transition for its subsequent identification in the interstellar medium. Present analysis of DCOOCH_3_ is aimed to provide a comprehensive spectral catalog that encompasses as much as possible the frequency coverage of the new generation far-IR and submillimeter wave observation facilities. A new measurement of the rotational spectrum of DCOOCH_3_ has been carried out in the JPL laboratory in the frequency range from 0.85 to 1.5 THz. The new data were analyzed jointly with literature data using the Rho Axis Method (RAM), a tool developed for the spectral analysis of molecules with large amplitude internal CH_3_ rotors. Twenty seven spectroscopic constants of DCOOCH_3_ have been fitted to 3763 transitions with maximum values of J=69 and Ka=36 of the ground torsional state with a standard (unitless) deviation of 0.97. With respect to prior work, this is a significantly better result that was obtained with 2060 more transitions while also achieving a better accuracy for the new parameter values.