He graduated from the University of Michigan with a Bachelor of Arts degree in 1966 and Stanford Law School with a Juris Doctor in 1970.

[4][5] Two dozen House Democrats, led by Representative Nancy Pelosi of San Francisco, opposed his nomination because of his perceived insensitivity to gays and the poor.

[10] Since retiring from the bench, Judge Walker has operated a private practice in San Francisco focusing on arbitration and mediation services, Walker Nakamura ADR LLP,[11] as well as lecturing at Stanford Law School and the University of California, Berkeley, School of Law.

[14] A San Francisco Chronicle columnist and reporter wrote in a commentary that Walker has an "aversion to harsh sentences for well-educated, well-heeled criminals and, in particular, perpetrators of securities fraud.

[17] Walker has presided over such notable cases as lawsuits over NSA warrantless surveillance;[18] the Apple Computer, Inc. v. Microsoft Corporation copyright infringement case;[19] the breach of TD Ameritrade's customer information database[20] Clint Reilly's antitrust litigation over the Hearst Corporation's purchase of the San Francisco Chronicle;[21] and Oracle's merger/hostile takeover of PeopleSoft, which was approved despite Justice Department opposition.

[23] On August 4, 2010, Walker ruled that Proposition 8 was unconstitutional "under both the Due Process and Equal Protection Clauses" and prohibited its enforcement.