Yes, it is legal to use an electronic Controlled Drug register provided it meets certain standards.
If you have a copy of Medicines, Ethics and Practice to hand, you can see a summary of the standards on page 107 of the 2019 edition. Clara meets these standards, as described below.
Every entry to the CD Register in Clara is attributable and the author of each entry is identifiable
Whenever a CD entry is created in Clara it is attributable to a specific person. This is done by selecting a staff member at the time of creating an entry.
Entries in Clara cannot be altered
Security and access control
Clara can only be accessed by someone with the username and password for that branch/organisation. Password resetting requires access to the email address for the user. The data itself is encrypted at rest and in transit, never leaves the UK, and is stored with an industry-leading cloud provider.
Database changes are continuously logged to allow us to restore the data to any point in time, and the whole database is backed up daily. For an additional layer of redundancy, your CD Registers are exported to PDF documents every evening and stored in a separate location from the database backups. There is also an option to backup your registers manually on demand.
Can be audited
Since the ways in which you can create and alter entries is strictly controlled, there is inherently a paper trail which can be audited at a later date.
Note: this article is not legal advice. Pharmacists are individually responsible for following relevant laws and professional standards, and for determining whether Clara is right for their pharmacy.