Like the use of the word Porto vs. Port, the US marketplace has some really odd labeling requirements. All other markets utilize the word "Port" and also "Over 40 Years Old" ... whereas here, the designations, "Porto" and "40 Year(s) Old" are used on the label.
Not positive, but I believe it has to do with the requirement to have an exact age on the label. Even though we all know that isn't the case with these Ports. I'm guessing, but I would assume it's based off a very old law that hasn't been updated.
I don't think it would be logical to use "Over" in front of the 10, 20 and 30 yr designations. The concept of these styles is that a 10 Year Tawny should be a wine with the flavour and vinous qualities of a port that has been aged in wood for 10, 20, 30 or over 40 years. If it was "Over 10 Years" the wine in the bottle could have the qualities of a 60 year old wine and still pass the test, which would be illogical as the same wine could also be labelled with each of the other three designations.
As to the validity of these designations, that is a completely different story.
Not positive, but I believe it has to do with the requirement to have an exact age on the label. Even though we all know that isn't the case with these Ports. I'm guessing, but I would assume it's based off a very old law that hasn't been updated.
Sorry, I should have clarified a bit more...This applies only to the USA as far as I know.
Here's an interesting one. This weekend I opened a Quinta do Noval 40 Over Year old Tawny. The label clearly read "OVER 40 YEARS OLD" and this was imported and bought here in the States. it was bottled in 2006, so I assume it was imported by the importer sometime within the year or so after that. I wonder if the reg's have changed here in the States?
I have a similarly labeled bottled of Noval 40, from 2007 ... also imported by Vintus. I think we'd have heard of a regulation to change the nomenclature of 40 year old Tawnies in the USA if they were relaxing that old rule. Could have been just a minor shipping error that went unnoticed, but that is purely speculation too.
When I imported wines I was required to have federal label approval for each wine (COLA - Certificate of Label Approval). It is then up to US Customs to check what is in the container to the paperwork. Customs does not check every container and checking wine containers is probably very low priority. Even if they checked they probably would not catch or care about a minor wording difference.
Shawn Denkler, "Portmaker" Quinta California Cellars