On 18 January 2022, Austria deposited the ratification of the Protocol to the Agreement on a Unified Patent Court (UPC) on Provisional
Application (PPA). Consequently, the PPA entered into force on 19 January 2022. During this period of provisional application, the
technical and infrastructural preparation works for the implementation of the new court must be completed.
Background
The unitary patent and the UPC are the building blocks of the unitary patent package, which will supplement and strengthen the existing centralised European patent-granting and enforcement system. The aim of the system is to offer users a cost-effective option for patent protection and dispute settlement across the participating EU member states.
The EU regulations establishing the unitary patent system have been effective for a long time (they entered into force on 20 January 2013), but they will only apply once Germany deposits its ratification instrument concerning the UPC Agreement.
Brexit
Various problems have arisen since 2013, one of the most significant being Brexit.
The entry into force of the UPC Agreement was conditioned on the deposit of the 13 instruments of ratification or accession, provided that the three member states with the highest number of European patents in 2012 (ie, Germany, France and the United Kingdom) featured.
The withdrawal of the United Kingdom from the UPC Agreement on 20 July 2020 brought about two key issues. One of those issues has been resolved by the preparatory committee through the substitution of the United Kingdom with Italy, which had the fourth highest number of European patents in 2012.
The second issue is that the United Kingdom was initially selected to host the central division of the UPC, with responsibility for life sciences, chemistry and metallurgy cases, which had to be located in London. This issue is not yet resolved; the provisional transfer of the seat's functions from London to Paris and/or Munich, or its relocation to Milan, is being considered. The alternative of renegotiation and re-ratification could be complicated and might have the effect of bringing the fine-tuning of the system to a halt once again. However, changing the headquarters without changing the UPC Agreement may cause some legal problems.
German ratification
Another big problem for the system was the difficulty for Germany to approve the PPA, the ratification of which was initially the subject of a constitutional complaint. On 27 September 2021, the German government finally deposited the instrument of ratification for the Protocol.
Current situation
As mentioned above, Austria deposited the PPA on 18 January 2022. It entered into force on 19 January 2022.
Now, the UPC Preparatory Committee will be able to formally start its work. Although there is no timeline set for the initial provisional application stage, the committee expects this stage to take approximately six to 10 months. The European Patent Office said recently that it expected it would take eight months.
As stated in a note published by the Presidency of the Council of the European Union on 24 September 2021, this stage includes the adoption of the secondary legislation of the UPC, including:

procedures;
establishment of a budget;
recruitment of judges and administrative staff;
election of a president;
final configuration and testing of the file management system; and
ensuring that all IT infrastructure is properly set up and secured.

When the final preparatory works for the UPC are about to be completed during the period of provisional application, Germany is expected to take the final and decisive step by depositing its ratification instrument concerning the UPC Agreement. This will trigger a period of four months, after which the UPC and the unitary patent system will go live. Currently, the system is expected to be up and running by the second half of 2022 or the start of 2023.
As the European Patent Office notes:

Unitary Patents may not cover all participating member states as some of them may not yet have ratified the UPC Agreement when it enters into force. Outstanding ratifications are likely to take place successively, so there may be different generations of
Unitary Patents with different territorial coverage. The coverage of a given generation of Unitary Patents will stay the same for their entire lifetime, irrespective of any subsequent ratifications of the UPC Agreement after the date of registration of unitary
effect. In other words, there will be no extension of the territorial coverage of Unitary Patents to other member states which ratify the UPC Agreement after the registration of unitary effect by the EPO.
Comment
Two EU member states, Spain and Croatia, are not party to the enhanced cooperation of the Agreement on Unitary Patent protection.
Poland is a member of the enhanced cooperation, but is not a member of the UPC Agreement.
It remains to be seen how the member states of the UPC will deal with the outstanding issues regarding the substitution of London with
another city and the different generations of unitary patents.