Lufthansa Technik AG v Astronics Advanced Electronic Systems & Anor

The court has equitable jurisdiction to award interest as ancillary relief on an account of profits for patent infringement under Patents Act 1977, section 61. Interest reflects the time value of profits retained by the infringer and need not depend on detailed evidence of how the money was used. The usual starting point is the date on which the cause of action accrued, although unreasonable delay by the claimant may justify adjustment where it caused the loss of use of funds. A final account of profits cannot ordinarily be converted into a provisional award merely because related foreign proceedings may create a risk of double recovery. Such issues are generally matters for the foreign courts applying their own law.

The judgment concerned consequential issues following the account of profits trial in two patent infringement claims brought by Lufthansa Technik AG against Astronics Advanced Electronic Systems, Safran Seats GB and Panasonic Avionics Corporation. The principal judgment had assessed profits and the court had made final orders for payment. The remaining issues were whether interest could be awarded on those profits, the appropriate jurisdiction and rate, and whether the English awards should be provisional because related proceedings in Germany and France might produce overlapping recovery.

The court also considered whether the defendants had established unreasonable delay by Lufthansa and whether the final orders should contain a recital, stay or permission to apply concerning possible double recovery.

1. Equitable jurisdiction. The court rejected the argument that equity could not award interest on an account of profits for patent infringement. The equitable jurisdiction to grant ancillary relief in support of equitable remedies extended to an account of profits under section 61 of the Patents Act 1977. The remedy was flexible and could be fashioned to achieve justice between the parties.
2. An account of profits is restitutionary. The infringer is treated as having conducted the infringing business for the patentee’s benefit and as holding the profits until disgorgement. Interest compensates for the time value of those profits and does not place the infringer in a worse position than if the infringement had not occurred. No detailed factual inquiry into the use of the money was required.
3. Section 35A. It was unnecessary to decide the statutory issue, but the judge considered that section 35A of the Senior Courts Act 1981 could also apply. A sum payable following an account of profits was capable of being treated as a statutory liability and an order for payment had been made.
4. Timing and delay. Interest ordinarily ran from accrual of the cause of action. Departure from that rule required unreasonable claimant delay which caused the claimant to be kept out of its money. Lufthansa’s delay in commencing the English proceedings and in beginning the account phase was not unreasonable or unjustified.
5. Rates and calculation. Interest on Astronics’ and Panasonic’s dollar liabilities was ordered at US Prime. Interest on Safran’s sterling liability was ordered at UK base rate plus 2 per cent. Profits accruing during each year or part-year were treated as arising at the midpoint. No tax deduction was made.
6. Finality and double recovery. The court refused to make the awards provisional, to stay execution, or to grant permission to apply. There was no established jurisdiction for a provisional award of profits in these circumstances. The principle of finality required the litigation to be brought to an end on the evidence available at trial. Any overlapping recovery was principally a matter for the German and French courts.
7. The defendants were ordered to pay the specified interest sums, subject to adjustment for the period between the end of February 2025 and 3 April 2025. The earlier provisional-payment direction was set aside and the payments were declared final.

First-instance judgment following the principal account-of-profits judgment, [2025] EWHC 375 (Pat), and a subsequent ex tempore ruling on liability for profits, [2025] EWHC 940 (Pat).