Yadayim 3:2

Anything that disqualifies trumah conveys second-degree impurity to hands. One hand conveys impurity to the other hand; this is the opinion of Rabbi Yehoshua. The Sages say that something unclean in the second degree doesn’t convey second-degree impurity. Rabbi Yehoshua answered them that Scriptures, which are unclean in the second degree, convey impurity to hands. They replied that Biblical laws can’t be derived from rabbinic laws, nor can rabbinic laws be derived from Biblical laws, nor can rabbinic laws be derived from one another.

Yadayim 3:3

Tefillin straps convey impurity to hands when connected to the tefillin; Rabbi Shimon says that tefillin straps don’t convey impurity to hands.