A federal judge late last week lashed out at the State Department's denial of visas for more than a dozen Nigerian witnesses set to testify in a pending trial over allegations that Chevron Corp. aided the Nigerian military in human rights violations a decade ago... The case stems from a nine-year-long legal battle by Nigerian villagers seeking to hold multinational Chevron Corp. liable for allegedly aiding the Nigerian military in attacks... Plaintiffs' attorney, Theresa Traber...asked [Judge] Illston to require Chevron to declare under penalty of perjury that it did not have a role in pressuring either the Nigerian government or the U.S. to withhold the visas. This brought a sharp protest from [Chevron attorney Robert] Mittelstaedt.