Taiwanese Private International Law ("PIL") Act effective on 27 May 2011 is a renovative result, which can be evaluated as a totally new legislation. Among such innovative reform, what is a specifically relevant issue to "Payment and Securities Settlement and Clearing" is Article 44 in Chapter 5 (Proprietary Rights) of Taiwanese PIL Act, providing for a special connecting factor for proprietary aspects of intermediated securities. I do welcome Article 44 given that it concretises the reality of cross-border securities collateral transactions made in the intermediated holding system and that abandons the lex rei sitae, the previous connecting factor for securities certificates, which is no longer appropriate one for intermediated securities. Especially, Article 44 can be evaluated as fairly aggressive in that it admits party autonomy modelling after the Hague Securities Convention in amid to the situation that Asian countries, including Korea, China and Japan, are reluctant to adopt a special statutory choice-of-law provision for intermediated securities. However, it is questionable that Article 44 provides as much legal certainty and predictability as intended by the drafters because unlimited party autonomy specified in Article 44 might infringe on vested rights due to the possibility of change of governing law, and complicate purely domestic transactions by making them international ones. Besides, the wording of Article 44 itself causes several uncertainty. In this regard, this paper further develops proper interpretive ways to attain the intended purposes of the legislation, but finds out that unlimited party autonomy for the proprietary issues of intermediated securities itself involves some unsurmountable demerits.