Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. We discuss in detail the search for a permanent electric dipole moment (EDM) of the 199 Hg atom reported by Griffith et al. [Phys. Rev. Lett. 102, 101601 (2009)]. The upper bound, d( 199 Hg) < 3.1 × 10 −29 e cm (95% C.L.), is a factor of 7 improvement over the best previous EDM limit for 199 Hg, provides the most sensitive probe to date for EDMs in diamagnetic atoms, and sets new limits on time-reversal symmetry violation in extensions to the standard model. This paper provides extensive discussion of the techniques used to search for the 199 Hg EDM and the implications of the new 199 Hg EDM limit for CP violation in elementary particle interactions.