EWJ 60 April 2025 web - Journal - Page 79
Lessons in Expert Witness Instruction
from UK Ruling in Shower Patent Dispute
by Alex Kyrtsoudis Associate, Bird & Bird
A recent UK Intellectual Property Enterprise Court
(IPEC) judgment in a dispute between shower manufacturers Kohler Mira Limited (“Mira”) and Norcros
Group (Holdings) Limited (“Triton”) highlights the
importance of instructions given to expert witnesses
in patent proceedings.
Decision
The Court had to decide the following legal issues:
Validity
Was the Patent:
1. Novel over the key piece of prior art cited, UK
Patent Application No. 2,274,985 A (“Deeley”)?
Expert witnesses are seen in virtually every patent
dispute that reaches the UK courts. Courts in the UK
tend to draw heavily on the opinions of expert witnesses and the role of experts is therefore often critical to the case outcome. Practitioners who regularly
instruct expert witnesses will be aware of the various
guidance on the use of expert witnesses in civil litigation proceedings in the UK, for example, Part 35 of
the Civil Procedure Rules (“CPR”).
2. Obvious over (i) Deeley in conjunction with the
common general knowledge, and (ii) the common
general knowledge?
3. Insufficient?
Infringement
4. Did Triton’s DuElec showers infringe the Patent?
As regards validity, the Court found the Patent was
novel over Deeley, not obvious, and sufficient, and
therefore the Patent was held to be valid. As regards
infringement, the Court found that Triton’s DuElec
showers fell within the scope of claims 1 and 4 of the
Patent, and so infringed it.
The judgment in Mira v Norcros [2024] EWHC 3247
(Ch) provides a useful reminder of the importance of
getting expert instructions right.
Background
Mira is the owner of UK Patent No. GB 2,466,504
(the “Patent”) which was granted on 10 July 2013
and relates to an electric shower which has two or
more outlets.
There were two main types of shower on the market
in the UK at the Priority Date (24 December 2008):
Expert witnesses: key takeaways
The judge spends a significant portion of the judgment analysing the parties’ expert witnesses. It is also
clear from the judgment that she preferred the evidence of Mira’s expert over that of Triton’s expert.
The full reasons for this must be appreciated from the
judgment itself, but here we summarise some of the
criticisms made of Triton’s expert by counsel for Mira,
much of which the judge agreed with, and draw out
three key learnings.
1. Mixer showers, supplied by hot and cold water
feeds which are mixed to produce water of the desired
temperature; and
2. Electric showers, which are supplied by a cold water
feed only, and contain one or more heating elements
inside their casing to heat the water.
1. Care should be taken when showing experts key
documents
Deeley was the key piece of prior art cited by Triton in
its validity attack on the Patent. Deeley describes a unit
fed by separate hot and cold water feeds, and containing an electric pump and a diverter valve. It is
therefore not an electric shower as it does not contain
a heating element, but is a mixer shower with a pump
to boost low pressure water supplies and two outlets
which can be selected by the user. Within Deeley there
is a cross-reference to UK Patent No. 2,219,497 B
(“McMaster-Christie”). Deeley refers to an alternative
invention being the incorporation of a water heater,
as is described in McMaster-Christie, to the invention
in Deeley.
With electric showers, the slower the flow rate of water
through the electric shower, the more time the water
will spend in contact with the heating element(s) and
the hotter the water will become. Therefore, if the flow
from the electric shower is restricted entirely or to the
extent that water flow is significantly impaired, the
water may be heated to a temperature which is dangerous to the user. At the Priority Date, electric showers on the market were limited to those with only one
outlet because of the risk of scalding if the water flow
is significantly impaired during operation of a diverter
valve to change the water outlet.
Mira’s Patent covers a solution to this problem such
that downstream of the heating element there is a diverter valve which is designed so that during
changeover of the diverter valve, the outlet ports are
never blocked to such an extent that water flow is
significantly impeded.
Mira claimed infringement of the Patent by Triton’s
‘DuElec’ range of electric showers which are marketed
in the UK and have two outlets, such as an overhead
shower and a hand shower.
EXPERT WITNESS JOURNAL
The parties took different approaches to the provision
of documents to their experts:
l Mira’s solicitors asked Mira’s expert to describe the
common general knowledge in relation to showers at
the Priority Date. Mira’s expert was then provided
with Deeley and, of his own accord, located and read
McMaster-Christie. He discussed Deeley and McMaster-Christie with Mira’s solicitors and was subsequently
provided with the Patent and other key documents
77
APRIL 2025
