"In doing so" vs "In so doing"

What's the difference between "in doing so" and "in so doing"? I believe they're interchangable -- but "in so doing" feels almost archaic to me.

Which one is most acceptable? Is there a difference?

Solution 1:

'In doing so', makes the verb (doing) the focus of the phrase. 'In so doing', is slightly reflexive, returning the emphasis back to what is being done. It is a finely nuanced distinction and the degree of formality in the latter phrase lends it to a negative connotation. "And in so doing the defendant caused....". Whereas the former phrase 'In doing so' is easier to link with a more positive action.

Solution 2:

John Lawler wrote in a comment just above:

They're both fixed phrases. The one with so before doing is more complex syntactically, and therefore more formal. Nobody talks like this; this is very old-fashioned written legal language. There are no meaning differences between them; which one to write (if either) depends on how formal the author wishes to appear. In doing so is Solicitor grade, but in so doing is Barrister.