363(c)(2)—Can’t use, sell or lease cash collateral, unless each entity w/ an interest in such collateral consents, or if the court approves.
a.    §363(a) defines cash collateral.  Basically, if cash comes from selling inventory and the inventory is subject to a valid SI, then the cash be subject to an SI.  Also, may just have an SI in cash or cash equivalents.
b.    If you want to use such prop, you have to go to court—not every time though.  Just need to provide adequate protection for such pro under 363(e).  According to Earth Lite, it isn’t good enough to just have an equity cushion for adequate protection—you need something more.