Since § 3 of the Clayton Act was directed to prohibiting specific practices even though not covered by the broad terms of the Sherman Act, [
Footnote 4] it is appropriate to consider first whether the enjoined contracts fall within the prohibition of the narrower Act. The relevant provisions of § 3 are:
"It shall be unlawful for any person engaged in commerce, in the course of such commerce, to lease or make a sale or contract for sale of goods, wares, merchandise, machinery, supplies, or other commodities, whether patented or unpatented, for use, consumption, or resale within the United States . . . on the condition, agreement, or understanding that the lessee or purchaser thereof shall not use or deal in the goods . . . of a competitor or competitors of the . . . seller, where the effect of such lease, sale, or contract for sale or such condition, agreement, or understanding may be to substantially lessen competition or tend to create a monopoly in any line of commerce."
Obviously the contracts here at issue would be proscribed if § 3 stopped short of the qualifying clause beginning, "where the effect of such lease, sale, or contract for sale. . . ." If effect is to be given that clause, however, it is by no means obvious, in view of Standard's minority share of the "line of commerce" involved, of the fact that that share has not recently increased, and of the claims of these contracts to economic utility, that the effect of the contracts may be to lessen competition or tend to create a monopoly. It is the qualifying clause therefore which must be construed.
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"Section 3 condemns sales or agreements where the effect of such sale or contract of sale 'may' be to substantially lessen competition or tend to create monopoly. . . .
But we do not think that the purpose in using the word 'may' was to prohibit the mere possibility of the consequences described. It was intended to prevent such agreements as would, under the circumstances disclosed, probably lessen competition, or create an actual tendency to monopoly."
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It is thus apparent that none of these cases controls the disposition of the present appeal, for Standard's share of the retail market for gasoline, even including sales through company-owned stations, is hardly large enough to conclude as a matter of law that it occupies a dominant position, nor did the trial court so find. The cases do indicate, however, that some sort of showing as to the actual or probable economic consequences of the agreements, if only the inferences to be drawn from the fact of dominant power, is important, and, to that extent, they tend to support appellant's position.
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We conclude, therefore, that the qualifying clause of § 3 is satisfied by proof that competition has been foreclosed in a substantial share of the line of commerce affected. It cannot be gainsaid that observance by a dealer of his requirements contract with Standard does effectively foreclose whatever opportunity there might be for competing suppliers to attract his patronage, and it is clear that the affected proportion of retail sales of petroleum products is substantial. In view of the widespread adoption of such contracts by Standard's competitors and the availability of alternative ways of obtaining an assured market, evidence that competitive activity has not actually declined is inconclusive. Standard's use of the contracts creates just such a potential clog on competition as it was the purpose of § 3 to remove wherever, were it to become actual, it would impede a substantial amount of competitive activity.
