While practicing law as an attorney, Judge Rassp handled workers’ compensation and Social Security disability cases since 1981 and was the principal of his own law firm from 1983 until April 15, 2018. In 2017, Judge Rassp was appointed as an adjunct professor of law at Pepperdine Caruso School of Law in Malibu, California teaching workers’ compensation law as an upper division class.

On April 16, 2018, Judge Rassp was appointed as a workers’ compensation administrative law judge and assigned to the Los Angeles WCAB District office. On December 26, 2019, Judge Rassp was appointed as the Presiding Judge at the WCAB Los Angeles District Office. In addition to his law practice, Judge Rassp was the Chair of Friends Research Institute’s West Coast Institutional Review Board for fifteen years. In September, 2005, Judge Rassp was appointed as a member of the Friends Research Institute’s Board of Directors and in October 2008, Judge Rassp was named Chairman of the Board of Directors for FRI, effective January 1, 2009.

In addition to his duties as an attorney and medical ethicist, Judge Rassp was appointed as a member of the State Bar Workers’ Compensation Law Section Executive Committee in April 1998 and became its Chair in 2000–2001. Judge Rassp was reappointed as a member of the Workers’ Compensation Law Section Executive Committee in May 2003 and was an advisor to the Committee under the California Lawyer’s Association until 2023.

Judge Rassp is the author of The Lawyer’s Guide To The AMA Guides and California Workers’ Compensation (LexisNexis® Matthew Bender) which is a widely used medical-legal treatise and updated every year since its first edition in 2006. In addition, Judge Rassp was a contributing author to The Complete Guide to Medicare Secondary Payer Compliance (LexisNexis). He is the editor-in-chief of the two-volume treatise, Rassp & Herlick, California Workers’ Compensation Law, Seventh Edition (LexisNexis). Judge Rassp wrote the commentary to the new WCAB Rules of Practice and Procedure that went into effect in January 2020 and January 2022. In August 2023, Judge Rassp is the editor-in-chief and principle author of the new LexisNexis “California Workers’ Compensation Discovery Handbook” which is part of the Rassp & Herlick treatise. Judge Rassp just issued an update on the Discovery book in 2025 and has published a new book called “Complex Issues of Employment in California Workers’ Compensation Cases.”

Judge Rassp is the keyboardist for three rock bands, “CC&R,” “Retro” and “Emerald City” and has played live shows throughout California.