ELI5: Explain Like I'm 5

Mosaic theory (US law)

Mosaic theory is a fancy phrase that grown-ups in law and government use to describe how they can figure out important secrets by piecing together lots of little clues. Imagine a big puzzle with lots of different pieces that all fit together. To make the picture on the puzzle, you have to look at each piece carefully and figure out where it goes.

Now imagine that instead of putting together a picture, you're trying to find out a big secret, like how to stop some bad guys from doing bad things. You might not have all the pieces of the puzzle right away, but if you keep looking at lots of little clues, you might start to see a pattern. You might be able to put together a picture of what the bad guys are planning, even if you don't have all the details.

That's kind of what mosaic theory is all about. It's a way for grown-ups in law and government to use lots of little pieces of information to figure out a bigger secret, even if they don't have all the pieces of the puzzle right away. Sometimes, when you put enough little pieces together, you can see the bigger picture.