Jason is a disputes lawyer specialising in insurance, professional negligence (construction and medical professionals), construction, product liability, and property litigation. He acts for blue chip construction and property companies, insurers, high-net-worth individuals, retailers, and estate managers.
He also attends Inquests, advising insureds and insurers on the procedure throughout. He has acted for medical professionals in negligence and malpractice claims. Jason’s experience extends to related regulatory issues to these types of claims, and inquests, and can conduct regulatory hearings with the assistance of Counsel.
Jason advises small and medium-sized civil engineering projects and companies, particularly with partnership, purchase agreement, shareholder, tax related and general commercial litigation issues faced by such entities.
He has provided non-contentious advice on property developments, working with lenders, landowners, contractors and developers on building contracts, warranties, and professional appointments.
Expertise
- Project disputes in the construction sector (adjudication, arbitration, and Technology and Construction Court disputes)
- Property litigation and dispute resolution
- All landlord and tenant issues
- Product liability disputes
- Professional negligence (construction and medical professionals)
Experience
Construction Litigation
- Claim by large construction company against an architect for failing to incorporate movement joints into the design of an office block in Manchester (headquarters for national law firm) (value of claim £2 million).
- Negotiated extension of time and settlement without payment of LADs re a claim against a piling contractor with design responsibility relating to the installation of foundations at a wind farm development as a result of poorly designed crane pads which failed load tests (value of claim £800,000).
- Settled at mediation a claim against a geotechnical engineer relating to a poorly designed flood defence where it was alleged that the defence could not withstand a full head of water, and leaked (value of claim £2 million).
- Developer’s claim issued in the Technology and Construction Court against a structural engineer for alleged poor design of steel frame leading to demolition of a large commercial building prior to practical completion (value of claim £2 million).
- Multiparty claim against a design and build contractor relating to cracks in the floor of a large distribution warehouse and the failure of the contractor’s stabilizing works, causing subsidence (value of claim unknown).
- Developer’s claim against an architect for poor design of wood furnishings and panelling in an Abbey, alleging that the design concept was unbuildable leading to extensive cracking (value of claim £1.5 million).
- Adjudication against a quantity surveyor following an allegation by a council of negligent project management which caused delay to the completion of a new school (value of claim £200,000).
- Defending a specialist plumbing subcontractor whose poor workmanship was alleged to have caused leaks throughout a large block of flats (value of claim £1 million).
- Provided advice on insurance and product liability aspects to L’Occitane Limited, after one of client’s contractors entered liquidation and a dispute then arose with the liquidators regarding what mutual credits and debits were owed by the parties
Product Liability
- Acting for an international manufacturer of electrical components – defending claims against them arising out of fires caused by defective miniature circuit boards in consumer units and then pursuing recoveries from “Part P” electricians for ignoring recall notices.
- Acting for a furniture designer and their insurers for producing an allegedly “unbuildable” design. Dealing with claims by or against the installer, a construction company and insurers following cracks appearing in the furniture. These claims involved product liability, construction, professional indemnity, insurance coverage and Third Parties (Rights against Insurers) Act issues.
- Acting for a world leading home appliances manufacturer defending claims relating to a repair action concerning defective printed circuit boards. Advising on when to admit liability, limitation defences, causation (competing cause), expert evidence, and issues relating to the spoliation of evidence.
- Advised Insurer of Home appliances on cases relating to fires from dish washer appliances, in particular in relation to whether Standstill agreement had expired
Property Litigation
- Edlington Properties Limited v J H Fenner & Co (2006). Had conduct of the case at first instance (Chancery Division) as well in the Court of Appeal. The underlying claim was worth £52 million.
- Fairgate International Limited v Citibank International PLC (2005) on a dilapidations claim issued in the Technology and Construction Court. Valued at £19 million. The reported element of the case concerned the disputed interpretation of a number of lease covenants, decided as a preliminary issue. The subsequent claim required analysis of complex expert evidence from building and valuation surveyors.
- Serving break notices, and notices under the Landlord and Tenant Act 1954.
- Seeking possession under the 1954 Act.
- Recovering rent and possession on various grounds.
- Dilapidations claims.
Professional Negligence (Non-Construction)
- Claim against a chartered surveyor re alleged failure to serve a counter notice in a rent review process concerning a letting in Brent Cross shopping centre (value of claim £1 million).
- Defending a tax advisor in a claim by a client relating to failed tax planning advice (value of claim £8 million).
- Defending a solicitors’ firm in a claim by a commercial property developer for failing to complete in accordance with the terms of a conditional contract for sale (value of claim £2 million).
- Acted in claims brought by claimants as the family of a person who died in care.
Non-Contentious Experience
- Drafting appointment documents for design consultants on office developments.
- Drafting and advising on leases and assisting with property transactions (commercial and high-end residential).
- Advising funders on construction documents prior to the purchase of commercial property.
- Drafting and advising on warranties.
- Drafting and advising on insurance clauses for insurance companies.
- Drafting and advising on shareholders and partnership agreements.
- Assisting a professional football club with its day-to-day affairs and documentation (including advising on players’ terms and conditions and service agreements for match-day providers).
- Advised on insurance related issues for care homes.
Contentious Experience
- Represented a foreign royal family member in respect of a serious personal injury allegation made by an ex-employee at their UK residence.
- Acting for Samsung in relation to a stolen shipment of batteries, intercepted on its way to a major car manufacturer supplied by Samsung.
- Advised on a subrogated claim against a sub-contractor for negligence in the supply and installation of bespoke decorative wooden panels for a display at a nature centre in Norway
- Acted for the insurers to a large and multi-centre private specialist vein centre who are an interested party to the Coroner’s Inquest into the death of a patient after vein surgery
Insurance-Medical
- Advised RiverStone Management insurers in the defence of a long-running claim by a professional boxer against the client, also brought against the boxing governing body, Senior Medical Officer and the fight promotor for alleged failures to safeguard the boxer.
- Advised the insurer of one of the UK’s largest independent providers of Intraoperative Monitoring used during spinal surgery on the defence of a claim relating to alleged failures during scoliosis correction surgery of a patient with Cerebral Palsy
- Successfully negotiated the defence of insurers to a medical and aesthetics company, in a claim for alleged negligence in the performance of a Cryotherapy treatment.
- Advised insurers on a claim made against an Optician with regards to the alleged failure to diagnose a malignant tumour on an optic nerve in respect of a minor who then died from the tumour
- Acted for the insurers to a large and multi-centre private specialist vein centre, which is an interested party to the Coroner’s Inquest into the death of a patient after vein surgery
Germany
- Defended a German sports car manufacturer in respect of a claim concerning an unexplained fire in the engine of a car.
- Acted for German based lift manufacturer, in a claim by the owner of an office block relating to a defect which caused a catastrophic failure and lift mechanisms to fall several stories.
Please note: The experience list above may include examples of work completed prior to joining Keystone Law.
Recognition
Recognised by the Legal 500 2025 for Clinical Negligence
Recognised by The Legal 500 for Product Liability: Defendant (2020-2025)
Recognised by The Legal 500 for Insurance and Reinsurance Litigation (2020-2025)
“Jason Kallis and Antony Colman are technically great, they fully understand the economics of a claim and both provide excellent levels of service. Both treat claims as a fully collaborative effort.” The Legal 500 2022
“Jason Kallis – attention to detail and ability to convey complex issues to lay clients is exceptional.” The Legal 500 2022
“Jason Kallis – Appreciates claims are a collaborative effort between stakeholders. Good communicator. Willing to advance a strong defence, although always conscious of the economics of a claim.” The Legal 500 2021
“Jason Kallis is attentive to the real life mechanics of the case and handles things in a dynamic fashion. Communication with the client is always at the right balance. Strategy and application of the law cannot be faulted.” Legal 500 2020
Recognised by the Legal 500 2018 for Insurance and Reinsurance Litigation
“Intelligent yet down to earth and gives concise and accurate advise which helps insurers get to the crux of the matter” Legal 500 2018
Jason Kallis is recognised by the Legal 500 2017.
Career
Jason qualified as a solicitor in 2000. Prior to joining Keystone Law in 2014, he worked at the following firms:
- Plexus Law
- DAC Beachcroft
- Mishcon de Reya
- Sherrards