The safeguards might just be that they won't sell you "large amounts of" the aggregated data unless you're clearly a profit-driven multinational corporation rather than a ideologically-driven individual. KYC and all that.

What about a profit-driven multinational corporation with political ties?

Say it is indeed possible to pinpoint individual congresspeople, as the grandparent suggested. If some of these congresspeople have a browsing history they'd rather not have made public, identifying them could leave them open to blackmail.

At some point the threat also just takes the form of "here's a list of random sites we totally made up and will tell people you visited". How well does blackmail like this even work? Even if somebody has every naughty site Trump has visited, where will you publish it and why are his supporters going to read it and believe you? Why will they not assume you made it all up?

Regardless of the source of the compromising information (browser history or other), one difference between factual and fabricated information is that you cannot deny the former without the risk of legal consequences, because denying it would be lying. Think perjury, for example (the Lewinsky scandal comes to mind).

And Trump would need to either ignore the claim made by the media, which could be seen as an admission of guilt...

Deny the claim, and then be later impeached for dishonesty.

Admit the claim, and then well, admit it.

IF some of the content is serious enough, it could surely be a foundation of a congressional hearing or perhaps even impeachment process? How can he respond to the questions there?

In any scenario... I can't see how he could "win" this? (Unless he is really innocent of anything questionable of course)

He was recorded admitting to groping women who weren't his wife. What on earth makes you think that his browsing history is going to bring him down?

He's not going to be impeached for dishonesty, the government is entirely run by his fellow Republicans.

He's not a Republican. He hijacked the party and beat the living shit out of every single one of them, and they fear him.

He is a Republican. He's the leader of the Republican party by way of winning the Republican nomination and the Presidency. The rest of the party may not like that, but the fact that Republican voters chose Trump over a more mainstream candidate demonstrates that mainstream Republican ideology is no longer relevant to the future of the party.

Which is why Trump probably won't be impeached, or even seriously censured - doing so would only cause an insurgency by Trump's supporters and it would weaken Republicans in the face of the Democrats. It would be suicidal.

I think we agree.

He's not the sort to make any friends. The GOP is just whistling sideways hoping the rest of America stops wondering what Trump is actually up to beyond the surface noise.

The NSA has it all already, and data is shared around via Five Eyes. The blackmail you speak of is likely already happening, just not at the multi-national corp. level, but higher.

I believe the correct term is lobbying not blackmail.

Because ideologically-driven individuals don't work for profit-driven multinational corporations? Because they're never hacked by ideologically-driven individuals? That kind of safeguard to me sounds like the worst of both worlds: Not meaningfully safeguarding anything, and lost business. A "clearly profit-driven multinational corporation" will (practically by definition) care about the latter.

That will be an interesting lawsuit to follow whether you are allowed to be discriminated against because of not being a profit-driven multinational corporation.

No, it won't and yes, you are, respectively and unfortunately.