SAN FRANCISCO — It was mostly a numbers game in the courtroom this morning during Day 4 of the federal trial challenging Proposition 8—how many couples got married, how many dollars did they spend, how much tax revenue has been lost as a result before and after the ban on same-sex marriage.

Plaintiffs opposing the same-sex marriage ban in California put on evidence to show that preventing same-sex couples from marrying hurts the local government by costing millions in revenue and commercial business. And, said San Francisco Chief Economist Edmund Egan, it costs in terms of public funding the city and county must spend to provide health coverage for gays without insurance, enforce a law to require employers to provide coverage for domestic partners, and provide for increased behavioral health care needs.

Egan testified that about 5,100 of the 18,000 same-sex couples who married between June and November 2008 were in San Francisco, that they spent at a rate of about $21 million per year on wedding expenses, to which would be added another several hundred thousands of dollars in associated taxes. Because of the same-sex marriage ban, said Egan, the city’s hotels are losing at least $2.6 million a year in business.

The purpose of such testimony, said Therese Stewart, Chief Deputy City Attorney for San Francisco, was to counter defendants’ efforts to claim that there is rational need for the governmental to ban same-sex marriage.

On cross-examination, defense attorney Peter Patterson tried to combine interim Census data on the number of same-sex households in San Francisco with Egan’s testimony to suggest he had vastly overestimated the costs. The Census data Patterson referred to showed 9,624 same-sex households in San Francisco; and by extrapolating from Egan’s data, Patterson said Egan would be predicting 14,599 weddings.

But on re-examination of Egan, plaintiff attorney Christine Van Aken enabled Egan to point out that every same-sex couple does not live together before marriage.

After Patterson tried to show only a small number of same-sex couples sought marriage licenses after November 2008, Van Aken had Egan point out that the November 4, 2008, vote approving Propostion 8 made it essentially pointless for any same-sex couples to apply for marriage licenses.

Testimony with two more witnesses is expected to be completed during the afternoon session, which begins at 1 p.m. Pacific time. Judge Vaughn Walker, who is presiding over the trial, acknowledged in court this morning the U.S. Supreme Court ruling which prohibits him from making taping or closed-circuit broadcast of the proceedings available beyond the courthouse itself. He announced he was, therefore, withdrawing his request that the Perry v. Schwarzenegger trial be part of the federal appeals court’s pilot program for making proceedings more widely available to the public.

Check back this evening for the full report of today’s testimony.