Oh, before we begin, I ought to mention: I'm about as anti SOPA/PIPA as it's possible to get. There's no need for you to come and widdle in my azaleas.
If SOPA and PIPA do in fact stay shelved then they may end up having been a huge own-goal for its supporters. Because its effects would be so wide and so strong, it's turned what was previously a multi-faceted debate about piracy into a big, simple, SOPA Vs. Pirates issue, and SOPA is so bad, so unbelievably, stupidly terrible, that anyone whose brain wasn't surgically removed at birth is going to find themselves, somehow, on the side of the pirates. After stories like this, it's not hard to see why people like Jim “Pirates are dirty thieves” Stirling have changed their tune – whether or not their views have actually changed, they've got to appear to be pro-pirate or end up on the dangling end of a virtual lynching.
However, SOPA presents a false dichotomy. Piracy is not a black or white issue, but a minor moral maze. To guide you though it, I present my list of 2.5 valid moral justifications for pirating games.
1: The game in question is not for sale due to geographical location or age.
Amazing as it may seem, not all games can be bought everywhere, especially if you live in Tuvalu or Tajikistan. If the game is simply not available for purchase in your country, and you can't get it via digital distribution, then pirate away. This is one of the very few cases in which “piracy is not a lost sale” is definitely true – the game could not have been purchased.
The second clause concerns games whose studios have either collapsed or stopped releasing the game – the point being that you can't buy it anywhere in a way that would give money to the developers. This used to be a fairly common scenario for older games, and in some cases it still is, but with the advent of Good Old Games and other such services, it is now often possible to buy old games without having to go second-hand. However, if you can't buy it, or it's been abandoned, then again, pirate away. Just check before you do. To borrow a point from TotalBiscuit, abandonware could even be beneficial to the game developers by keeping interest in a franchise alive and increasing the possibility of a sequel.
2: You already own a copy of the game in question
This is a simple one. A lot of my games were bought many years ago and are still on discs. If those discs get scratched or broken beyond repair, I see no reason why I shouldn't download another copy. If you lose a card from a deck of playing cards, you're perfectly entitled to scribble the number and suit onto the joker or bridge score card and carry on playing. This does to some degree cover the issue of emulation, though that's a can of worms I'm saving for my next fishing trip. Also note that this does not cover “I'm going to buy it if I like it when I finish it” or some other equally fatuous excuse. Especially if the buying later consists of a Steam sale or a bundle.
2.5: You could not afford/would not have bought the game in question
There's a reason that this is a half-point, so before you scroll down to the comments and tell me what a dirty free-tard I am, allow me to explain. First of all, let's look at the harm that pirating a copy of the game does.
If it's a straight up decision between clicking on Steam or The Pirate Bay, then the harm is obvious: the developers have lost a sale. They get less money and fewer sales, reducing the likelihood of a sequel and the survival of the studio. That's pretty clear. However, a lot of pirates claim that they either couldn't afford or wouldn't have bought the game anyway, and thus their download doesn't count as a lost sale, and thus there is no harm done. And yes, if that is genuinely the case, and that person would never, ever have bought the game under any circumstances, then it's not a lost sale.
There is a reason that this was a half-point, and it's this: these reasons practically never apply. You say that you wouldn't have bought it, but you were interested enough to go to the effort of pirating it, which is normally more than the effort required to buy it on Steam. You say that you couldn't afford it, but you probably could if you saved up or waited for a sale at some future point. If you really, genuinely can't afford it, then there are a tonne of free and really, really cheap games. I'm currently a student living almost entirely off my student maintenance loan, which is around £5000/year (around $8000, I think?), and I can still afford to buy games. I don't buy many: my most recent purchases, in reverse chronological order, are Magicka, Skyrim, Sequence, Orcs Must Die and Deus Ex: Human Revolution. Most of those were bought on or shortly after release (Magicka is the exception), at full price. What I'm saying is that while theoretically these are justifiable reasons, I find it extremely hard to believe that they ever really apply.
So, there we are. Those are, to my mind, the only morally justifiable reasons for downloading games illegally. If you don't fit those criteria, then please, please, stop trying to justify your actions as being harmless or even praiseworthy in some way. Definitely stop trying to make pirating a game because you're too greedy or lazy to pay for it a political act. Stop using examples of bad behaviour by publishers or politicians as justification. Saying “I don't like that they outsourced the boss fights in DXHR so I'll pirate it” is effectively the same flawed logic that leads publishers to say “I don't like that they keep pirating the games so I'm going to drop DRM on it till it screams”. Yes, they can be dicks. They shouldn't be, and neither should you. One might think that this kind of basic reasoning was taught in kindergarten, but apparently not. If you really disprove of a company's DRM or other actions, then just don't buy the game.
In short, please, please stop making excuses. You're fooling no one but yourself.