It's the principle

The News and Observer blog on grammar had the April 23 entry headlined 'It's the principal,' which quoted an Associated Press report that said 'payments of both interest and principle...' The other day a news draft landed at the news desk which said 'the Election Commission has in pricipal decided to....' Again, 'principal' and 'principle,' as in the college principle, have so often been interchanged in the news drafts and less so in the final versions that they have come to be concidered pet peeves, only to no dismay of the writers and editors.