This response is long. But it’s accurate.
The BBC report got the demands slightly wrong. The students never formally asked for a “cancelling” of the agreement; they went it “sent back” (退回) to the Executive Yuan, and they don’t want the Executive Yuan to give it to the legislature for another review until the “supervision law” is implemented. Once that happens, though, the services pact can go through the proper review process at the Legislative Yuan and get endorsed as it inevitably will.
Their argument is that there is not really a formal way of handling agreements with China. The government signs each pact behind closed doors and then tosses it, eventually, to the Legislative Yuan for endorsement. At issue this time around is what happened March 17.
The KMT wanted to start a meeting, headed by lawmaker Chang Ching-chung, to let the legislature’s eight committees review the trade-in-services pact item-by-item as the party had promised the DPP. But they were unable to start the meeting due to opposition from DPP lawmakers, who occupied the podium in an attempt to prevent Chang from presiding. Undeterred, he retreated to a corner with a wireless microphone, from which he declared the review meeting had begun, and within less than minute’s time, declared the meeting adjourned and the pact reviewed.
That means that, if things went the way the KMT wanted, they would be able to put the pact to a floor vote among all legislators, which the KMT with its majority would easily win. In other words, they managed to side-step the review process entirely. The only reason the plan failed is that these students began occupying the legislature the day after.
Chang’s iffy-at-best explanation for how he forced the pact through the committee session is that he labeled the pact an “executive order;” indeed, the law governing the powers of the LY does explicitly state that executive orders go into effect within three months of being issued, even if lawmakers have not successfully completed their review of the order. The question is whether an economic agreement can count as an executive order in the first place. On that matter, even Chang is uncertain, saying that it would take a legal expert to make the call, and yet his party insists the pact has already been reviewed. Depending on who you ask, a floor vote may not even be necessary. If the three-month regulation stands, the Executive Yuan can announce the service trade pact has gone into effect whenever it feels like it, lawmakers be damned.
Suspicious, though, is why the administration waiting until nine months after the pact was signed to invoke the three-month rule.
The whole debacle speaks to a lack of standardized practices when dealing with controversial treaties. Trade pacts probably have a relatively limited impact on Taiwan’s future, but can you imagine what would happen if the Ma administration unilaterally signed a peace agreement with China and pushed it through the legislature in this way? What about, hypothetically, an agreement to unify with the mainland or a formal declaration of independence? Protesters are worried because Ma’s clout in his own party and his role as the head of government mean the Legislative Yuan is basically a rubber stamp parliament for him (when the otherwise impotent DPP isn’t making a raucous, that is). They feel the only way to improve supervision over how cross-strait deals are handled is to introduce a law formally requiring it.
I hope that helps answer your question.