Which preposition to use with lawfulness

of Occurrences 30%

To those for whom the lawfulness of re-marriage for an innocent divorcee is, like the rest of their religious beliefs, a matter of opinion, the scruple of a character like Madge Riversdale is unthinkable and incredible.

in Occurrences 1%

If social evolution takes the right course, the practice of polygamy will be abolished; and the maintenance of its lawfulness in canonical works will mainly be a survival of a bygone phase of development.

Which preposition to use with  lawfulness