BOSTON — Opponents of a proposed bioterrorism research laboratory at Boston University Medical Center won a victory last week when a state judge ruled that the basis used to approve the so-called Biolab was “arbitrary and capricious.”

Responding to a lawsuit filed by 10 area residents who were concerned about the public health implications of the lab, Suffolk Superior Court Judge Ralph D. Gant ordered further study and consideration of alternative sites and worst-case scenarios.

The lab has been a political football, with some local public officials, including Mayor Thomas Menino and Gov. Mitt Romney, supporting it.

The BU Biolab, part of the Bush administration’s “anti-biological terrorism” program, would be a “Biosafety Level 4,” or BSL4, facility, which would do research on highly infectious and deadly bacteria and viruses like Ebola and anthrax.

A Massachusetts Institute of Technology lab worker told this reporter, “Even at Levels 1 and 2 you have to be careful of contamination. Having this lab in a place like Boston is scary. You can kill a lot of people if they [the pathogens] get out.”

Residents near the proposed lab site were further alarmed when, in 2004, three BU scientists were infected with a deadly strain of the tularemia bacteria at a BSL3 facility. The lethal sample was mixed in with a benign strain. In the 1950s, the U.S. military developed deadly forms of tularemia to use as a biological weapon.

One of the groups opposed to the Biolab, the environmental justice organization Alternatives for Community and Environment (ACE), says there are only three BSL4 facilities in the country. The best known is the Centers for Disease Control near Atlanta. The Bush administration is funding the construction of two more.

The BU Biolab would be the only one of its kind in the middle of a densely populated area. The lab site is in a neighborhood with a density of almost 17,000 persons per square mile. Other BSL4 facilities are in areas with 3,500 persons or less per square mile.

Community residents only found out about the Biolab plan in the spring of 2003, when another local environmental grouping, Safety Net, discovered that BU had applied for the necessary funding and permits.

Residents organized and compelled the university to hold community meetings. While BU tried to convince the residents of the safety of the Biolab, the neighbors were not convinced. They organized a campaign of letter writing and petitions to oppose the lab. Despite the protests, the Bush administration approved the funding for the lab in September 2003.

The closed way in which BU has operated, with no community input at the beginning, has led area residents to wonder if the lab will do more than research defenses against bacteria and viruses. ACE and Safety Net point out, “For 20 years, the federal government can mandate the research to be conducted in the lab and require classified research.” This could include development of biological weapons.

Opposition to the Biolab has spread beyond local community residents. In 2004, 165 scientists, academics, doctors and public health experts signed a letter addressed to the university, Mayor Menino and the Boston City Council opposing the lab project. Many organizations, including the two trade unions representing Boston Medical Center workers, have also opposed the project.