Yet according to Mark Zecca, a Philadelphia attorney who served in the city's Law Department for two decades — including many years, he said, as counsel to the Historical Commission — the commission's reversal Monday was flawed in other ways, too. In an interview Tuesday, Zecca argued that common law established by previous judicial decisions stipulates that so long as a quorum is present at a meeting, all that is required for a valid vote is a majority of the quorum. The Historical Commission defines a quorum as eight members — meaning the original five votes in favor of preservation on Nov. 10 would stand.