Google 'keyword warrant' in Minnesota now part of national privacy debate

What about when you are using stealth mode or incognito or whatever your browser privacy settings is?

Do what you want to conceal your traffic (incognito, VPN, different search engine). If you can't be traced easily, that's up to LEOs to adapt and find legal ways to overcome. People do this in public too (wear masks, disguises, etc...). LEOs have found ways to overcome some of these methods too. If you or anyone is going to ask if there are sure ways to guarantee security, I'm going to say no, there isn't. I work in cybersecurity and we never tell clients that anything is a sure thing. So, you build a defense in depth capability, consistent to what you can afford to do and with what addresses the threat best while considering the risk of not doing anything. The bad guys then have to circumvent those barriers (like keeping their ego in check while they search for news or "how tos" on the crime they are about to commit or just committed) to avoid getting caught. This method does not target anyone specifically, other than getting leads to narrow down a search for a bad guy.