Is it always followed by another construction that also means "regardless of" (as in いかんによらず)? If so, is there a difference in nuance with and without いかん?
According to my teacher, you can use this expression without the のいかん.
Also, the word before にかかわらず needs to have at least two meanings built into the words, for example: 性別, 国籍, 晴雨 etc. If not have to have to include at least two words with opposite meaning.
This expression can also be used with verbs, with dic + nai , for example:
There's another page with the shortened form: http://www.renshuu.org/index.php?page=grammar/individual&id=263 (They are linked as similar entries at the top of the page).
As for the noun restriction, it's not that I doubt what your teacher said, but can you ask her/him to comment on these sentences (taken from a grammar text): 国民の賛意のいかんにかかわらず、その提案へ国会で可決されるだろう。 理由のいかんによらず、殺人は許されないことだ。
