The short answer is: "No".
In May 1976, Steven Spurrier and Patricia Gallagher organized a wine tasting that has become known as the Judgment of Paris. Here, wines from France were tasted alongside some wines from California, and the latter acquitted themselves very well in the opinions of the tasters.
These sorts of comparative tastings had been conducted before, but mostly within the USA, whereas the Judgment took place in France itself with French judges; and, more importantly, it occurred in conjunction with the US Bicentennial celebrations. It therefore attracted much more media attention than any of the previous tastings. Indeed, it may well be the third most important event in the social and economic history of wine in the USA, after the imposition and then repeal of Prohibition.
However, the results of the Judgment were very variable among the tasters. Hardly any of them agreed closely with each other about the quality scoring of the wines, and especially about which wines were the best among the 10 reds (bordeaux grapes) and the 10 whites (chardonnays). This raises the question as to what other people thought about the relative quality of those same wines, at that same time.
This question is answerable to some extent by looking at the tastings of the Vintners Club, based in San Francisco. This club was formed in 1971 to organize weekly wine tastings (usually 12 wines). This club is still extant, although tastings are now monthly, instead of weekly. For our purposes here, the early tastings are reported in the book Vintners Club: Fourteen Years of Wine Tastings 1973-1987 (edited by Mary-Ellen McNeil-Draper. 1988).
One of the Club's tastings was an attempt to to evaluate the results of the Judgment tasting nearly 2 years afterwards (January 1978), as reported in a previous blog post (Was the Judgment of Paris repeatable?). However, the Club also tasted the individual wines before May 1976, usually in comparisons including other California wines (ie. those not chosen by Spurrier for the Judgment). Indeed, the success of the wines at these tastings seems to have played some part in establishing their respective reputations, leading to Spurrier choosing them to take part in the Judgment.
So, we can compare the Judgment wines quite independently of the Judgment itself, but in the same time period. This is an interesting exercise; and it emphasizes the point made at the time by Frank J. Prial (New York Times June 16 1976, p. 39), about the variability of wine assessments: "One would be foolish to take Mr Spurrier's little tasting as definitive."
Here, I will focus on the six California cabernets and six California chardonnays, each of which was tasted at the Vintners Club at least once before and once after the Judgment. All four of the French Bordeaux reds were also tasted at least twice at the Club, but not always both before and after the Judgment; and only one of the four French Burgundy whites was ever tasted at the Club.
Immediately preceding the Judgment, four of the six California chardonnays were tasted at the Chardonnay Taste-Off (February 1976), and four of the six California cabernets were tasted at the Cabernet Sauvignon Taste-Off (March 1976). These comparative Taste-Offs at the Vintners Club are explained in an earlier post (Wine tastings: should we assess wines by quality points or rank order of preference?).
The results of the various tastings are shown in the two graphs. The scores for each wine are the average from those tasters present on each occasion, based on the standard UC Davis scoring system, as used by the Vintners Club. The dates of the tastings are shown relative to the Judgment of Paris (May 24 1976).
In order to facilitate comparisons, the wines are listed in the graph legends in the order of their results at the Judgment itself (ie. highest score to lowest).
Among the cabernets, the Stag's Leap, Ridge, and Heitz wines were pretty much equal at every tasting. These wines were consistently rated as superior to the other three red wines, but we should not see any one of these three as being better than the other two. Interestingly, the only occasions on which the Stag's Leap wine was judged to be "best" was at the Judgment itself and again at its re-enactment. Also, note that the results for the Mayacamas wine were rather erratic, especially given its third-place result at the Judgment.
Among the chardonnays, the Chateau Montelena wine did not do well. Indeed, the Chalone wine consistently scored better than the Montelena, except at the Judgment of Paris itself. Indeed, most of the white wines scored better than than the Montelena except at the Judgment and its re-enactment. Also, for the whites it was the David Bruce wine that received particularly erratic results, on at least one occasion performing very well.
Finally, it is worth noting that 9 of the 12 wines received much higher scores at the 1978 re-enactment of the Judgment than they had before the Judgment tasting. It is hard not to see a subjective post-hoc bias in this result.
Clearly, the unique accolades heaped on the Judgment's two "winning" wines were not justified by the Vintners Club comparisons of the 12 wines. The Montelena white, in particular, was usually bested by the Chalone wine; and the Stag's Leap red was never better than those from Ridge or Heitz. This emphasizes the unreliability of single tastings for assessing wines — the outcomes depend too strongly on the circumstances, particularly the tasters present. Furthermore, some wines obviously received very variable assessments, sometimes being rated much more highly than on other occasions — either these wines were showing bottle variation or they were in an unusual style (as has been noted for the Bruce wine).