TODAY HOUSE opponents of the Senate-ratified treaties turning the Panama Canal over to Panama get to take their last shot. They will be striving to reject the House-Senate conference report on the legislation that puts the treaties into effect. Almost everyone else is irritated or bored to find the discussion still going on, but the opponents are still gnawing away. They are using every tactic they can to destroy solemn international agreements that Senate ratification has already made the law of the land and whose scuttling by the House now would cause endless damage to the interests and the good name of the United States.

It is enough to consider just two points as the House takes up the conference report. In the conference, the House team took a decidedly tougher stance than the Senate and, under the leadership of House Merchant Marine Chairman John M. Murphy (D-N.Y.) prevailed on the critical points: on making the new commission that will operate the canal until the year 2000 subject to the annual appropriations control of Congress, on putting the commission under the Department of Defense, on requiring the five American commissioners (of nine) to vote as a bloc, on ensuring that all property transfers be approved by the full Congress, and on protecting the American workers essential to the operation of the canal. For the House to instruct its conferees to fight for specific objectives, and then to reject the report registering so many victories, is absurd.

Perhaps in recognition of the weakness of their case on the merits, the opponents, led by Rep. Robert Bauman (R-MD.), have shifted ground and are now emphasizing that recent revelations of a Soviet combat presence in Cuba compel the United States to keep its old tight hold on the canal. The argument is lame. The treaties, and especially the implementing legislation, nail down for the United States precisely the military rights and base structure in Panama that it would need to deal with any military contingency arising from Cuba. And of course there is scarcely a better way to prepare for regional political contingencies than by resolving the canal question to the American advantage, as the new legislation ensures that the treaties would do.