At first, it was not known whether or not EU Member States should ratify the agreement, given that the European Commission placed the treaty solely under the EU`s responsibility.  However, in July 2016, it was decided to characterize CETA as a «mixed agreement» and therefore ratify it through national procedures.  The European Commission has proposed CETA as a «mixed agreement» that must be ratified by each EU member state in addition to the European Parliament. This process could take several years. In the United Kingdom, the agreement must be submitted to Parliament for a period of 21 sitting days. The agreement can only be ratified if the 21-day deadline has passed without either parliament deciding not to ratify it. In the case of such a resolution of the House of Commons, an additional 21 days is set in place for the House of Commons to again raise objections. The government announced on 21 May 2018 that it would soon launch the formal ratification process in the UK. CETA was introduced in the House of Commons on June 13, 2018. On June 26, 2018, a debate was held in the House of Commons on CETA. The United Kingdom ratified CETA on 8 November 2018. The EU agreement with Canada is referred to as a comprehensive economic and trade agreement, short for Ceta.
In September 2017, Belgium asked the European Court of Justice to rule on the compatibility of CETA`s dispute resolution system with EU law. The agreement could only enter into force after the ECJ had issued its opinion, nor when the European Court of Justice found that CETA was incompatible with EU law.  On 30 April 2019, the European Court of Justice concluded that the CETA dispute settlement system was compatible with EU law.  Critics argue that the agreement is overly business-friendly and may lead to a reduction in regulatory standards. Opponents of CETA are still unconvinced of reforms to investment rules and argue that these foreign investors could grant special privileges and deter governments from legislating in the public interest for fear of litigation. The Belgian government has asked the European Court of Justice to rule on the compatibility of CETA with EU law. In April 2019, the ECJ decided that CETA was compatible with EU law. The process of ratifying trade agreements – in particular the fact that CETA was applied on an interim basis – that is, before the parliaments of EU Member States had the opportunity to ratify it – was also criticised.
On 26 March 2014, Federal Economy Minister Sigmar Gabriel wrote an open letter to EU Trade Commissioner Karel De Gucht, in which he said that investment protection was a central sensitive issue that could ultimately decide whether a transatlantic free trade agreement would be approved by Germany. He also noted that there was no need for investment arbitration procedures between countries with well-developed legal systems. Regardless of the outcome of the negotiations on the future relationship between the UK and the EU, whether the transition period ends without an agreement between the EU and the UK or an agreement covering only part of the current trade relationship, it is likely that at the end of the transition period there will be immediate changes to the TRADE and investment rules between the UK and the EU.