More than 500 Boston residents will gather at the Law School this Saturday to plan a strategy for the first major statewide campaign against restoring the Massachusetts death penalty.

The full-day conference--open to the general public--will offer strategy sessions and workshops aimed at organizing a grass-roots movement which could forestall the referendum item on the 1982 state ballot. Flora Haas, a journalist and an adviser to the new coalition, said this week.

A constitutional amendment to restore the death penalty would require approval by two constitutional conventions to be held in successive sessions of the legislature and ratification in a public referendum. One convention last fall approved the proposal.