  In this document, we summarize the main capabilities of the James Webb Space
Telescope (JWST) for performing observations of Mars. The distinctive vantage
point of JWST at the Sun-Earth Lagrange point (L2) will allow sampling the full
observable disk, permitting the study of short-term phenomena, diurnal
processes (across the East-West axis) and latitudinal processes between the
hemispheres (including seasonal effects) with excellent spatial resolutions
(0.07 arcsec at 2 {\mu}m). Spectroscopic observations will be achievable in the
0.7-5 {\mu}m spectral region with NIRSpec at a maximum resolving power of 2700,
and with 8000 in the 1-1.25 {\mu}m range. Imaging will be attainable with
NIRCam at 4.3 {\mu}m and with two narrow filters near 2 {\mu}m, while the
nightside will be accessible with several filters in the 0.5 to 2 {\mu}m. Such
a powerful suite of instruments will be a major asset for the exploration and
characterization of Mars. Some science cases include the mapping of the water
D/H ratio, investigations of the Martian mesosphere via the characterization of
the non-LTE CO$_2$ emission at 4.3 {\mu}m, studies of chemical transport via
observations of the O$_2$ nightglow at 1.27 {\mu}m, high cadence mapping of the
variability dust and water ice clouds, and sensitive searches for trace species
and hydrated features on the Martian surface. In-flight characterization of the
instruments may allow for additional science opportunities.
