Would a search engine be allowed to prioritize their content? I notice that when I type anything into google, google-related searches appear first. I know this is probably not what's happening, but it begs the question, could a search engine prioritize its own products and services legally?
Due to competition/antitrust laws it can be illegal, more so if the search engine is dominant in the market. This has actually been realized in the EU where they fined Google €2.42 billion for abusing their market dominance and favouring their own Google Shopping service in search results. For further information, that fine has been specifically addressed on this site. In the US, this has not yet come to such a dramatic penalty, but there have been investigations. The FTC has investigated similar search results manipulation among other antitrust issues, but ultimately decided not to file a lawsuit as the changes to the search algorithms "could be plausibly justified as innovations that improved Google’s product." Following this inaction, as of November 2017, the state of Missouri is also investigating Google on the same issue. I'm not certain if manipulating search results on its own is illegal, but with market dominance (like what Google has), it certainly is.
You mean like Unilever, and countless others do? Yes. Many, many companies control a stable of brands, often of competing products. This is particularly prevalent in grocery lines (cleaning, food, beauty products) and motor vehicles (there are dozens of brands of motor vehicle but only a handful of automotive companies). Clearly, these products have different features (improvements) – you are entitled to segment your market anyway you like. If they are actually produced by the same company, keeping that secret would be virtually impossible. If they were separate companies (even with licencing agreements etc.), well, they are not the same company even if they have common ownership. As for having a monopoly: if you hold a patent you are allowed to have a monopoly, if you don't, expect to see knock-off rocket boots on the shelf in a week.
Not necessarily, but also possibly. Google Books may (or may not) have a license to distribute images of the book covers in question. This license would be between Google and the owner of the copyright of the book cover. Just because Google has a license to distribute the image of the book cover to you does not mean that you have a license to distribute the image of the book cover to your customers. However, depending on jurisdiction, using the book cover to identify a book might also be legal under relevant fair use statutes. It is also possible that the particular book cover is not protected by copyright. For example, a particular book cover might have entered public domain. If this question is not a hypothetical, you should probably consult a lawyer.
I don't think any appellate court has given an opinion on whether encryption creates a reasonable expectation of privacy. This is not surprising as only recently has it come to light that the government may have weakened encryption protocols and asked for backdoors in order to aid in decryption. However, Orin Kerr, professor of Law at George Washington University School of Law wrote this article in 2001. He argues that encryption does not create a reasonable expectation of privacy. He says: the Fourth Amendment regulates access, not understanding. Once you introduce your communication into third party systems (or the garbage :P), they may give it up to the government. If the government happens to be able to understand that communication, so be it. He shows how this conclusion is consistent with how the courts have ruled on "reassembly of shredded documents, recovery of deleted files, and the translation of foreign languages". Note that the reasonable expectation of privacy test is only one of the tests used to determine whether a search or seizure is reasonable. Another test is the "trespass" test which deems an interaction to be a search per se if there is a trespass on a person's personal effects. It was used before Katz and was reiterated recently in US v Jones (2012). Regardless, your question is still meaningful because the two tests are used alongside each other.
In the UK and USA (and I imagine other jurisdictions) there have been laws that explicitly provide for orders obliging entities to (A) provide access or information and (B) keep the order secret. For example, in the USA the Stored Communications Act, Fair Credit Reporting Act and Right to Financial Privacy Act authorise the FBI to issue National Security Letters (Wikipedia, EFF, EPIC, Lawfare). These are an administrative subpoena, without prior approval from a judge, for meta-information (e.g. phone numbers dialed or email recipients addressed but not the content) of communications relevant to national security investigations. They typically contain a non-disclosure requirement prohibiting the recipient of the NSL from disclosing its existence or the FBI's demands. There have been challenges on First Amendment grounds to the non-disclosure aspect but, so far as I'm aware, they have all ultimately failed. Some of their non-disclosure requirements may eventually expire under other laws. In response, so-called 'warrant canaries' (Wikipedia) have been developed (and gone a bit further than the original idea) - these are intended to allow entities to relatively passively warn of such an order having been received if not the detail of the order. However, they can be legally risky in that they might be seen by a court as trying to circumvent the non-disclosure requirement and therefore breaking it.
Law enforcement only investigates crimes, and they have significant discretion regarding which crimes to investigate. If they considered a crime to have occurred in your case, they could certainly seek a court warrant requiring Google to turn over IP addresses. More likely, you might have standing to seek relief in civil courts. In such a case, you could try to get the civil court to issue a subpoena for a third party like Google to provide IP addresses. Of course, you could have your civil suit contested by the counterparty, and even if not the court may decline to issue a subpoena, and if even if it issues one the third party may object to the court, or simply decline to comply with it.
As far as I can tell, whenever GitHub redistributes code, it adheres to all of the requirements of the GPL/BSD etc. For example, it never gives away code without including the license text, and it doesn't claim to add unpermitted restrictions to the code. The section you're concerned about is this: That means you're giving us the right to do things like reproduce your content (so we can do things like copy it to our database and make backups); display it (so we can do things like show it to you and other users); modify it (so our server can do things like parse it into a search index); distribute it (so we can do things like share it with other users); and perform it (in case your content is something like music or video). That section isn't worded very precisely, but I understand this to mean they want to reproduce your content in full, not just the code without the license text attached. They want to display your content in full, as you provided it. They want to modify it internally (i.e. they are not redistributing this modified form) in order to allow searching. To the extent that they display code-snippets as search results, that is likely defensible as fair use (search engines are frequently cited as examples of successful fair use defenses). GitHub appears to be acting consistently with the GPL when it reproduces, displays, modifies, and distributes code that you upload. If I'm correct about these facts then nothing that GitHub does with the code goes beyond what the many contributors to a GPL project have explicitly permitted, or what is otherwise permitted by fair use law. If you had some code with a more restrictive license, you might not be able to simultaneously comply with that restrictive license and GitHub's License Grant. Consider the scenario where you have some code that is licensed exclusively to you, and you are not given permission to reproduce or distribute it. In that scenario, the code's license prevents you from agreeing to GitHub's request for a license grant.
An Art 15 Subject Access Request (SAR) “shall not adversely affect the rights and freedoms of others.” It would be a grave violation of privacy for an email provider to search its users' account contents. It is therefore likely that the email provider would refuse to fulfil that subject request, unless required to perform a search via a court order. Instead, the SAR could be directed to the account holder (Alice or Dave), if they are subject to the GDPR. Depending on the exact legal framework, emails might be protected under confidentiality of communications rules, making such searches similarly illegal to wiretapping. At least in germany, I am fairly certain that an email provider would be criminally liable if they were to disclose emails from their users' email accounts to a third party.