The agreement between Australia, Canada, Japan, Mexico, New Zealand and Singapore entered into force on 30 December 2018. However, Canada`s biggest reservation was a conflict between the percentage of a vehicle that must come from a CPTPP member country to operate duty-free, which was 45% below the original TPP language and 62.5% below NAFTA. Japan, which is a major exporter of automobiles, supports significantly lower requirements.  In January 2018, Canada announced that it would sign the CPTPP after receiving mandatory ancillary letters on culture and bilateral agreements with Japan, Malaysia and Australia on non-tariff barriers to trade with any other CPTPP member country. The Auto Parts Manufacturers` Association of Canada strongly criticized the increase in the percentage of spare parts that can be imported duty-free and found that the United States was moving in the opposite direction by demanding stricter import standards in the ongoing nafta renegotiation.  While much of the CPTPP remains unchanged from the original TPP, trade experts say there are significant differences. These were largely modifications or cancellations of measures promoted by Washington and unpopular with other participants. In June 2015, U.S. Senator Rand Paul, a Republican from Kentucky, rejected the law to speed up Congressional ratification of the TPP based on the secrecy of the trade deal.
 Georgetown University Professor Marc L. Busch and McGill University Professor Krzysztof J. Pelc notes that modern trade agreements are long and complex, as they often address not only tariffs, but also non-tariff barriers, such as different standards and rules. Due to the steady decline in tariff barriers since World War II, it became increasingly likely that countries would erect trade barriers in the form of non-tariff barriers. Domestic companies often lobby their own governments to adopt rules to keep foreign companies away. The TPP addresses many of these „disguised trade restrictions,“ for example by „basing these measures on agreed science; make the rule-making process more transparent; and to provide foreign exporters with the opportunity to make substantial contributions to the formulation of these measures.  On October 25, 10, 2018, New Zealand ratified the CPTPP, bringing to four the number of countries that had formally ratified the agreement.  Some thought that the original TPP would likely bring China`s neighbors closer to the United States and reduce their dependence on Chinese trade.           If the TPP were ratified, it would have strengthened U.S. influence on future rules of the global economy. .