E-discovery has become even more crucial in the era of big data as companies struggle to locate and—on a good day—preserve all of the electronic information at their disposal. It seems like a relatively straightforward notion. But the larger volume of data requires more sophisticated tools to get the job done, which means that the legal departments and law firms who can afford the investment will be cutting bigger checks, while ones that can't may have to explore other alternatives. Here's a detailed look at 5 of the biggest e-discovery challenges that practitioners facing practitioners that are unlikely to go away any time soon.