OFFER you today a rather unusual discussion between AssistantAttorney General William Bradford Reynolds, whose letter appears elsewhere on this page, and ourselves. We say unusual because it is not simply an argument about principle or policy, on which reasonable people might disagree, but an argument about what a particular Supreme Court decision said. You would think there would not be much to argue about in that, and you would be wrong.

The opinion in question is Mobile v. Bolden, which was decided almost two years ago. We believe it set a new and unnecessarily tougher standard for the courts to use in determining whether a particular voting system is discriminatory. This is the view of civil rights advocates, who want to amend Section 2 of the voting rights bill now being considered by Congress in order to return to the pre-Mobile standard. Mr. Reynolds believes the Mobile case signaled no change and that the standard it set for proving discrimination is not difficult to meet. He therefore sees no need to amend the voting rights bill.

In a series of cases decided before Mobile-we mentioned two of them in our Jan. 26 editorial--the courts had looked at the way an electoral system was operating to see whether, for all practical purposes, minorities had been excluded from the process. For example, the fact that, in a county that is 40 percent black, not a single black had ever been elected to office would be some indication--though not conclusive proof--that a discriminatory system was in place. The courts also looked at other evidence, including the history of discrimination in the county, the operation of the nominating process and the responsiveness of elected officials to the needs of minorities. If the total picture presented by all these effects showed discrimination, then the electoral system was held to be invalid.

In Mobile, the Supreme Court held that it was not enough to show the discriminatory effects of the voting system. The plaintiffs in Mobile had to show that legislators who devised the voting system had a racially motivated intent to discriminate. Since the legislators in question had all been dead for many years, the plaintiffs could not meet the burden of proof, and they lost the case.

According to Justice Byron White, who wrote the majority opinion in an earlier voting case, the new and more difficult intent standard imposed by Mobile is "flatly inconsistent" with the earlier opinions. This is also the view of litigators who have argued these voting rights cases for years, according to their testimony before the Senate Judiciary Committee last week.

>Is it difficult to prove that local legislators intended to discriminate when they devised a voting system? Yes. In the two recent cases where plaintiffs were successful, the "smoking gun" to which Mr. Reynolds refers was in fact found. In one case, members of the legislature themselves were available and willing to testify on the intentions of the lawmakers. In another case, an at-large voter system was adopted at exactly the same time as blacks became eligible to vote in the Democratic primary.

>In most cases, however--especially those where the challenged system has been in place for many years--it is far more difficult to prove intent. Some cases that were decided in favor of plaintiffs before Mobile have already been reversed for failure to meet the new standard. Another, which was decided in favor of plaintiffs last March, will be argued before the Supreme Court later this month. Meanwhile, Congress has both the right and the obligation to direct the courts by statute to use the pre-Mobile standard in evaluating voting systems. Three hundred eighty-nine members of the House, by their recorded vote, and 63 senators, by their cosponsorship of the House-passed voting rights bill, have already done so.