Need to get back after someone hired some mercs to attack you? Hire your own mercs to attack their mercs! After all merc contracts need to be a matter of public record after all, otherwise their pirates. After all, legitimacy is a very valuable thing.
I'm going to disagree a bit there, but on grounds of how the contracting is actually done in the BTU. Which is a very fair point upon which to quibble given the nature of the thread. But here it is: Just because a contract was bonded thru ComStar doesn't mean it's subject to FOIA requests or the BTU equivalent
That being said though, military force is much more acceptable in the BTU than it is in international circles in the real world, and that's a cultural survival from the Ares Conventions that were hammered out in the Age of War. When the Conventions are mentioned in a historical context, there's usually a mention about how the criticism of those Conventions is that they made warfare a politically viable option of first resort. I conceptualize this as warfare is pretty much the option you choose when instead you'd take someone to court in the real world. In the BTU, fighting a raid over an IP breach is as normal as a frivilous lawsuit is today. A merc company doesn't have any more reason to hide their identity than a lawyer does in the real world. Especially in late SW contexts, fighting is much more like a ritualized (but very violent) sport than true warfare.. mercs that get beat on the field of battle concede defeat and go on about their business. Again delving into my headcanon, but I don't imagine mercs generally get any more (or less, to be fair) butthurt about getting beat on the field of battle than sports teams do on the pitch or gridiron. See the Dragoons-Big Mac rivalry for the main example here. Of course, the Waco Rangers-Dragoon "rivalry" could be a counterexample, but I like to think of the former being more representative of the merc industry than the latter. To each one's own.
Something that I've always wrangled with was how exactly Hiring Halls
work. First of all, the Hiring Hall has to be more than a physical compound with negotiation rooms. It's clearly got to be a network moreso than a location, or else you'd have to physically go back to Galatea or Outreach after every contract to get a new contract. And sequeing off of that, I also envision a Hiring Hall as having vendors as a significant part of that network. Vendors that sell everything from mech parts to uniforms to Prickly Pear Rations. I don't mean to rehash the disagreements I've had with others upthread, but just to reiterate I've always seen the Great House Armies as being only the tip of the iceberg when it comes to the military industrial market. If you're a defense manufacturer, you'd be crazy to NOT sell to the secondary markets as well. Besides, I just can't get past the suspension of disbelief for ordering replacement parts from some sort of Space Amazon.com that we've never heard about. It's that, or the big meta problem of there being people wherever PCs go holding on to valuable military materiel who for some reason only sell to people who happen to be PCs.
Whether or not that all is indeed "true" for the fantasy universe, something I really wrangle with is OPSEC for Hiring Halls. I know megamek isn't canon, but bear with me here. From a sample contract, the following information is all present:
1) Which Great House is hiring
2) Which Great House is the target
3) Which planet is the target
4) Start date of the contract
5) What forces exactly they require
6) What forces you'll face
All that info is required for the game to function, whether it's megamek or a RPG. But here's the thing, that info being viewable by anyone who happens to be walking thru the Hiring Hall (or has passed vetting process for said Hiring Hall) could give that information to the entity listed in 2) and basically render the entire mission militarily unviable. And there's basically no way to prevent it from happening, not unless your headcanon allows for ComStar to crack any and every cipher ever going out over a HPG. Now, to be fair, maybe you do. But even if ComStar sees MIIO or ISF spoiling info back home about a raid coming to one of their House's worlds, would ComStar actually DO anything about it? Not so sure. They're getting their brokers' cut no matter what.
So, the fact that noone ever uses contract info targeting their faction to spoil those contracts seems to indicate it doesn't happen. The WHY of it just ever seems to go into head canon. I personally presume that you really don't get all the information presented in a meta sense. There's serious reasons why you don't dare ever give out each of those 1-6 until the contract is already signed, but there's game balance and even lore reasons why each piece individually has to be given. You could argue that there's some sort of NDA that a Hiring Hall uses, that way you're obligated to keep military secrets that you glean just by browsing available contracts secret, even if you don't sign said contract(s). I don't see how it's enforceable without an omniscient ComStar, however. I kind of like the idea of turning what we've seen in the meta game mechanics on its ear: a merc captain looking for contracts doesn't to a Space Google search on the Hiring Hall computer boards for available contacts... the Hiring Hall instead has the merc put in his criteria (I won't work for Kurita, I can put 12 mechs in the field, I'm available starting on this day, I'll do these kinds of missions, etc) and then based on the criteria he gets contact info for negotators with pending contracts that meet his search criteria. Then, in the course of the negotiations face to face (or hologram to hologram, or whatever) the vetting of the mercs can take place and the mercs can begin to get more militarily sensitive info before formally signing on.