Molecules in living organisms have a chiral bias -- that is, if they are not isomorphic to their mirror image, then one form will almost always be dominant over the other. E.g., glucose is a common organic molecule found in most, if not all, living things\.; but it's mirror image is virtually absent.
If there is life on other worlds, it may, of course, bear little resemblance to life on Earth -- but if it resembles terrestrial life, one might expect unbalanced chiralty in molecules in the life form.
Inorganic matter, not produces from living molecules, do not show unbalanced chiralty.
So: If the James Webb telescope should be capable of viewing chiralty of molecules on other planets (a tall order), and if if it should spot unbalanced chiralty on another world, that would strongly suggest that there is life on that world.
Attached is a .pdf of a research article on the subject.
-- Saul
chirality_of_biologcal_molrcules.pdf