The question of whether Americans are well-informed enough to vote intelligently on major national issues was debated yesterday by a Senate subcommittee weighing a proposed constitutional amendment that would permit direct enactment of laws by popular vote.

Other concerns expressed before the constitution subcommittee of Sen. Birch Bayh (D-Ind.) included whether the majority, it given the choice would disregard rights of minorities or if powerful special-interest group would dominate lawmaking at the polls.

Nearly all of the witnesses favored the concept of the National Initiative Amendment introduced by Sen. James Abourezk (D-S.D.), but Bayh said he had "serious reservations" about whether the idea would work at the federal level.

The amendment would require to be placed before all voters questions petitioned by 3 per cent of those voting in at least 10 states in the previous presidential election.

Laws approved at the polls would take effect within 30 days and could not be repealed or amended by Congress for two years, except by a two-thirds vote of both houses, although they would be subject to presidential veto. The initiative procedure could not be used to declare war, call up the militia or amend the Constitution.

Del. Walter E. Fauntroy (D-D.C.), who supports the idea, noted that voters in the District of Columbia gave 83 per cent support last month to a citizen initiative, referendum and recall process. Twenty-three states have a similar procedure.

Abourezk said the amendment, co-sponsored by Sens. Mark O. Hatfield (R-Ore.) and Mike Gravel (D-Alaska), is "a serious constitutional proposal which is commanding the support of liberals, conservatives, Republicans and Democrats alike."