When a bill as controversial as the pension reform is debated in the Assemblée Nationale, opposition MPs tend to drastically increase the number of amendments and prolong the back and forth with the Sénat. The government has the option of using Article 49.3 of the Constitution, which allows the bill to pass the Assemblée without a vote.
Paragraph 3 of Article 49 allows the prime minister, "after deliberation by the Council of Ministers," to force a bill through the Assemblée Nationale with no vote. The only alternative to prevent the bill from passing is then to overthrow the government.
When the prime minister triggers this procedure, MPs have the option of tabling a motion of no confidence within 24 hours. If a majority vote is obtained, the law is rejected and the government collapses. The next logical move would be for the president to dissolve the Assemblée and call early elections.
If the motion of no confidence is rejected, the government wins its gamble: the law is passed.
Since the 2008 constitutional reform, the use of Article 49.3 is limited to one bill per parliamentary session, without counting the state budget and the social security budget, for which the government can use it without restriction.