The firm announced today that it has hired partners Ian Kirby (pictured) and Jonathan Day from Arnold & Porter's London office.
Kirby, a patent litigator, has already joined the firm. Day, a solicitor and trade mark attorney, joins on September 22.
Managing IP understands that a third solicitor, specialising in life sciences, is also expected to join the firm soon.
The move comes ahead of the launch of the EU Unitary Patent and Unified Patent Court, expected in 2016.
Hugh Goodfellow, the firm's head of life sciences, told Managing IP: "With the launch of the Unitary Patent and UPC, we believe these additions will enable us to offer clients a comprehensive IP service."
Historically, there has been a clear divide in the UK between firms of patent and trade mark attorneys and firms of solicitors, who often referred work to each other.
However, in recent years this has broken down as patent firms such as Marks & Clerk and HGF have set up associated litigation practices, and others such as D Young and EIP have added solicitors. Going in the other direction, some law firms such as Olswang have hired patent attorneys.
Carpmaels' initiative goes further than some other firms as it is understood that all the new members will have equal status to the existing partners, and be part of the same firm.
It comes as many European firms are evaluating how best to advise clients on the UPC, including whether they need to add expertise or new offices.
"As patent attorneys we are very experienced in opposition work, which we think will prepare us well for UPC proceedings. Adding solicitors gives us extra experience in for example evidence gathering and witness preparation, but most importantly of all, for the strategic insights which only come from years of experience conducting litigation across Europe," said Goodfellow.
He added that the new hires are part of a long-term strategy: "We expect that we will make further additions in the future as the UPC develops."