If I recall correctly, after the results of the test came in, the city conducted some preliminary inquiries that yielded some expert testimony that the test was discriminatory, but those were never completed, and the only evidence that the city formally introduced in court was the results of the test.

The oral vs. written dispute is a bit ironic. It seems to me that oral exams would have been disfavored in the earlier years of the civil rights movement, because it's harder to conduct those tests in a race-blind fashion. The test results can be skewed, even unconsciously, if the tester knows (or even thinks he or she knows) what race the applicant is, and I have to think there was a time when there was serious concern that that bias would have run squarely against black applicants. I wonder what kinds of protections are built into those tests nowadays.