AFAIK if you actually get detained and questioned at airports, your drive will already get imaged before any password is even tried. You may be able to get away with this on a mobile device where this feature isn't generally expected (because who uses Linux on a smartphone in the first place).
I always wonder at what scenarios like these are supposed to be about. If saying no is not an option, pissing off your captors by giving them fake info probably isn't either.
I don't know what law enforcement would be looking for on my work drive, but if saying no is no longer an option, my encryption password isn't worth getting shot over.