centra

Type Ia supernovae have been successfully used as standard candles in cosmology finding the first direct evidence for an accelerated universe filled with an unknown dark energy component. Today, systematic uncertainties dominate the error budget of dark energy, and extinction from intervening obscuring material in the line of sight still remains a primary concern. It has been shown that not all supernovae follow the standard Milky Way extinction curve and that the assumption of a common extinction law for all of the objects has important implications for cosmology; especially if there is an evolution of the populations with look-back time. I review the current state of extinction studies towards type Ia supernovae and present the multiple techniques (including polarization and integral field spectroscopy) we are using to address this elusive, yet fundamental, question.