CODEX is the proposed ultra-stable optical high-resolution spectrograph for the E-ELT, which will use novel Laser Comb calibration techniques and an innovative design to open a new era for precision spectroscopy. With its unique combination of light-collecting power and precision, CODEX will make it possible to directly measure the acceleration of the Universe by monitoring the cosmological redshift drift of spectroscopic features at cosmological distances. CODEX will also allow the assembly of the first sizeable sample of earth-like planets in the habitable zones of their stars with the radial velocity technique. CODEX will take this technique to the level of cm/sec radial velocity stability - a factor of about 20 improvement compared to current instruments. These are two of the scientific results anticipated for CODEX, which will be complemented by a wide range of spectacular science in stellar, galactic and extra-galactic Astronomy as well as Fundamental Physics. All the critical technology items are available or (as for the Laser Frequency Comb) are in an advanced state of testing. CODEX is located at the E-ELT coudé focus that will cover the visible range from 370 to 710 nm and provide a resolving power R~120000 with an aperture of 0.8 arcseconds in the sky.