Abstract: This presentation describes the electromagnetic compatibility (EMC) tests performed on the Integrated Science Instrument Module (ISIM), the science payload of the James Webb Space Telescope (JWST), at NASAs Goddard Space Flight Center (GSFC) in August 2015. By its very nature of being an integrated payload, it could be treated as neither a unit level test nor an integrated spacecraft observatory test. Non-standard test criteria are described along with non-standard test methods that had to be…