Under what circumstances can the stereochemistry at nitrogen atom be faithfully retained and identified?
You could try to lock the conformation of structure. For example, derivatives of a  1-azabicyclo[2.2.2]octane system could have a chiral nitrogen, and the fact that the substituents are tied back prevents inversion of the nitrogen. Quinine has this kind of structural moiety.

This example isn't exactly what you're looking for, but it does it by using diastereocontrol to limit the amount of undesired isomer: J. Org. Chem. 2004, 69 (3), 714–718.

As Ivan suggested, you can hold onto the lone pair with something. Here's an example where metal coordination prevents inversion: Inorg. Chem. 2012, 51 (15), 8516–8523.

There are plenty of others. I just did a quick search on the JACS website for stereogenic nitrogen.