This is a phrase I've run into a couple of times, and is really starting to bug me. I can't figure out what the "tate" part of it should be in kanji, if there even is a regular kanji representation for its root, and my dictionary only has "ni totte"--to, for, concerning, as regarding, something of that nature. It's been a pretty crucial part of understanding the sentences I've found it in, and I can't find any examples containing it that I can figure out the whole meaning of without it in order to get a better idea of what it means. Anybody?

Here's an example sentence:

しかし平日以外や通常業務の時間外であると、往々にして警察は監獄法をたてにとって被疑者の外部交通権を実際に遮断してしまいます