A proposed referendum to ban the research and production of nuclear weapons in Cambridge has apparently gotten around the major legal roadblock keeping it off the November ballot, as the State Ethics Commission has effectively allowed the Cambridge City Council to place the question before the voters.

The binding initiative campaign, which received the requisite number of certified signatures, was stalled at the August 8 city council meeting when the councilors failed. On a 4-4-1 vote, to put the Nuclear Free Cambridge question on the ballot. The one abstention was Councilor David Sullivan, who had publicly supported the referendum but could not vote on it because his position with the Secretary of State's office election commission placed him in a conflict of interest.

formal advisory opinion, the commission-charged with overseeing possible abuses of state conflict of interest and financial disclosure statutes-ruled Monday the Sullivan could vote on the issue. Sullivan said yesterday that the statement explained that "the Secretary of State did not have enough interest in the local matter."

Before the commission ruling, the fate of the referendum lay solely in the hands of the Supreme Judicial Court. After the original council vote, Nuclear free Cambridge proponents used the legislators, arguing that state law only gave them ministerial duty to place the question on the ballot, not the discretion to keep it off.

The court had the argument Tuesday, and had planned to rule on the issue soon. But all parties involved agreed yesterday that if the council were to vote to place the referendum on the ballot, the court case would be moot.

A council revote is not automatic after the ethics commission ruling, but Councilor David A. Wylie said he will reintroduce the proposal at next Monday's meeting. Because of various parliamentary technicalities which opponents are likely to use, the actual council vote will probably not take place for another three weeks.

The council's original tie vote on the question was clearly split along party lines, with opposing votes coming from conservative councilors and supporting ones from more liberal members.

No Precedent

Although other cities have passed nuclear free referendums, Cambridge is the first community to consider such a measure where nuclear weapons are currently manufactured.

Cambridge, which is also the largest city to consider a nuclear-free referendum, passed a similar though nonbinding measure in 1981.

Kenneth Cohen, legal counsel for Charles Draper Laboratories-the local firm that would be most acutely affected by the proposed ban on nuclear research and production and an intervener in the Supreme Judicial Court case on behalf of the council-has challenged the city's right to place the measure on the ballot.