The D.C. Statehood Convention voted last night to prohibit the death penalty under its proposed constitution. It also moved to broaden criminal suspects' rights of habeas corpus and against double jeopardy beyond similar provisions in many other states.

In a 25-to-6 vote, convention delegates added the death penalty ban to its bill of rights, rejecting arguments by some delegates that the issue should be left to the proposed new state's legislature.

In the same manner, the convention adopted on first reading a double jeopardy provision that would not only prohibit a suspect from being tried twice for the same offense in a state court but block his trial in state court if he has already been tried under the same general facts and circumstances in a federal court.

In most other states, local prosecutors retain the power to try suspects regardless of whether they have been through a federal trial for essentially the same offense.

But Ward 5 delegate Michael Marcus, member of the preamble-and-rights committee that pushed the broadened language, contended the main purpose of the provision was to prevent "prosecutorial harassment" by the state "pursuing trial after trial after trial" against the same defendant for the same offense.

The convention also voted for unlimited availability of habeas corpus--the right of a suspect to an immediate hearing on the claim that he has been unconstitutionally or unlawfully detained.

In the U.S. Constitution and in many state constitutions where it is mentioned, habeas corpus may be suspended in case of rebellion, invasion or other major threat to public safety.

The convention's language breaks "new ground" said Ward 3 delegate Courts Oulahan, urging delegates to use the language of the U.S. Constitution instead.

Again, Marcus argued that threat of rebellion or invasion was not significant. In a real emergency, the president could suspend the habeas corpus provision of the U.S. Constitution, which would supercede the state constitution, he said.

Other delegates said the purpose of the broadened habeas corpus language was to overcome limits on the use of habeas corpus specified in recent Supreme Court rulings.

The convention's language would permit defendants to petition for habeas corpus "at all times" and "without limit" as to the number of times.

The convention also voted to abolish the traditional doctrine of "sovereign immunity" for the proposed new state, meaning that all of its agencies and employes could be sued for civil wrongs without the customary consent of the state.