You're right, my statements are too cut and dry, and the law is a big swamp of ambiguity.
I'm not a lawyer, these are my layman interpretations of judges' interpretations of congress's interpretations of laws passed by previous congresses and interpreted by previous judges.
In the US, copyright law protects five rights (with the last one duplicated with a stupid "on a computer" variant). Note that they cover distributing copies and publicly performing, the do not cover obtaining copies.
They cover some distribution (for example, they can't prevent reselling), and some duplication. Obtaining didn't need to be covered in a pre-digital world, because the act of obtaining didn't necessarily involve duplication. And in a digital world, it still doesn't need to be covered, because the act of "obtaining" is actually digitally duplicating as well. Either you are digitally duplicating something you just bought for personal use (and are automatically and instantly discarding the original digital copy you just bought (which never leaves the digital storefront), due to the nature of how computers work), or you are digitally copying from a copy you don't own, and are in violation of the duplication rights.
Suppose there are three copies of the same digital work.
I have a physical CD I bought, that's on my desk. I rip it to my computer. That "copying" is authorized, because it's copying something I already own for personal use.
I go to Amazon.com and buy the same digital album. My purchased album is on their computer. I copy (download) it to my computer. I'm copying, for personal use, what I own. It's authorized copying. Because of the nature of computers, the album I purchased never actually leaves Amazon.com's server, it's just copied to my computer.
I then go to a mp3 pirating site, or whatever, and download the same album from there. I'm copying something from a copy that I don't legitimately have access to. That act of copying is the unauthorized one.
I now have three identical blobs of binary data on my computer. Three identical copies of the same music album. Two were legitimately acquired, and one of them I had to infringe copyright to get. It's not data ownership that's covered by the law, it's data duplication and distribution (and performance and etc...).
For other nations, in Canada and in most of the EU that supports the EU Copyright Directive of 2001, there is a specific exemption in the law, a personal copying exemption, that allows making and even acquiring copies for personal noncommercial use.
I'm pretty sure the USA also has provisions for personal copying - though I'm too lazy to look it up at the moment. I'm not sure if it covers "acquiring" copies.
They vary based on nation, but may effectively say if you own it one media format you can download it to achieve a format shift.
USA also permits format shifting, time shifting, and etc...
However, USA courts have specifically said downloading music is also infringing. I'm not aware of an exception saying, 'unless you already own a copy' - but there might be one, I just never heard of that.
In the Napster lawsuit, the court said:
https://www.law.cornell.edu/copyright/cases/239_F3d_1004.htm
We agree that [...] Napster users infringe at least two of the copyright holders’ exclusive rights: the rights of reproduction, and distribution. Napster users who upload file names to the search index for others to copy violate plaintiffs’ distribution rights. Napster users who download files containing copyrighted music violate plaintiffs’ reproduction rights.
They covered both the uploading and the downloading. In the uploading case it wasn't even 'uploading', but opening the door of their computers so other users can retrieve it.
The Napster case references an earlier case from a different court, where users were downloading ROMs for Sega games. The case wasn't about the users, but about the person providing the tools to copy the games and distributing them. However, in that case, the court clearly says that the users downloading the games were also infringing.
http://digital-law-online.info/cases/41PQ2D1705.htm
"The BBS users were encouraged to download games from the BBS in order to avoid having to buy video games cartridges from Sega."
"By utilizing the MAPHIA BBS, users are able to download and distribute one or more copies of Sega video game programs from a single copy of a Sega video game program on the MAPHIA BBS, and thereby obtain unauthorized copies of Sega’s copyrighted video game programs.
This unauthorized copying of Sega video game programs works to decrease Sega’s sales of video game cartridges."
"Even if the users are only playing the games in their own homes and even if there are currently only a limited number of users that have copiers, unrestricted and widespread conduct of this sort would result in a substantial adverse impact on the market for the Sega games."
"By downloading the games from the BBS, users avoid paying for the games. Sherman’s conduct in providing the BBS for uploading and downloading games, and offering for sale the copiers on which to play these unauthorized games, facilitated the users’ conduct. This conduct, if widespread, would adversely impact the market for Sega games."
"He knowingly allowed others to upload and download the Sega games, and expressly solicited others to upload games to his BBS. He offered for sale copiers that play and copy Sega downloaded games from disks. His business, Parsec Trading, sold or planned to sell copiers. Parsec Trading had a policy of giving customers limited free downloads after they had purchased a copier. This evidence shows that Sherman intentionally contributed to the users’ infringement of Sega’s copyright, and that he intended to profit in sales of copiers. Sherman has offered nothing to rebut this evidence. Therefore, the Court finds that Sherman’s contributory copyright infringement was willful."
It seems clear to me that these two courts think that both uploading and downloading constitutes infringement of copyright, though in different ways.
This creates precedent. While not locked in stone, it's fairly safe to assume that other courts will accept and follow the same line of reasoning, unless a higher court decides differently, or unless Congress creates new laws.
In the USA, court decisions are also part of the law - not just the laws passed by congress. The courts are clarifying for the digital age how the courts interpret laws that were passed by Congress. While true that these weren't federal courts, they were district courts, in California, they were interpreting nation-wide law. Unless a higher court comes along and overrules them or clarifies further, or unless congress writes new laws that supersede or repeal the old laws, this is what 'the law' is.
In another case, there was a site called MP3.com, which required users to prove they owned a legitimate copy before streaming downloading/streaming music to them.
It was legally purchased copies that MP3.com purchased, and users themselves had to prove they owned a copy, and even then it was infringing because the downloading was considered "performing". I think this is because the copies they were downloading/streaming weren't the same copies, but I'm not sure. I can't find the actual court decision online, only things talking about it.
I'd very much love to know if you're correct about only-uploading. This subject interests me alot. And again, I think the laws need to be greatly overhauled and clarified.
I just assumed the RIAA is more willing to target uploaders because it's easier to prove they are knowingly ("willfully") infringing, and because they do more damage and are probably easier to track, and less terrible PR-wise (i.e. "they are distributing, not just downloading!").
Unfortunately, we might not be able to have a clear-cut answer.