Corporate and Commercial

Request a call back

Does “Commercial Common Sense” Play a Part in the Interpretation of a Contract?

by Phoebe Holland

Invicta Law’s Phoebe Holland (Trainee Solicitor in the Corporate and Commercial group) breaks down the key messages on the legal principles of good faith, implied rationality and commercial common sense from the recent judgement of Cathay Pacific Airways -v- Lufthansa Technik [2020] EWHC 1789 (CH).

Good faith and relational contracts

It is an established principle that there is no legal doctrine of good faith in general application within the English law of contract. However, a duty of good faith will arise under a specific class of long-term contracts, termed ‘relational’. These require a high degree of communication, co-operation and predictable performance based on mutual trust and confidence, involving expectations of loyalty outside of the specific wording of the contract (Sheihk Tahnoon [2018] EWHC 333).

In the recent case, Lufthansa Technik (LHT) sought to establish that the contract with Cathay Pacific Airways (CX) was relational and therefore subject to a duty of good faith. In his thorough Judgment, John Kimbell QC accepts the notion of a relational contract and its interplay with good faith, however, rejects the proposition that the contract between LHT and CX was relational based on the facts relating to that contract. The circumstances where a contract will be categorised as relational are limited; far more is required than merely a lengthy term.

The duty of implied rationality

LHT also submitted that the contract with CX was subject to the “duty of rationality”, which CX had infringed. John Kimbell QC confirms the nature of an implied “duty of rationality” as an exception to the general rule that contractual rights are enforceable regardless of whether they are exercised in a reasonable manner.

Where there is a sophisticated commercial arrangement where both parties have received expert legal advice, there is no justification for the court to interfere with the nature of the bargain struck.

Commercial common sense and mutual understanding

Finally, LHT contended that the mutual understanding the parties shared during negotiations invalidated CX’s actions, as they were contrary to the true interpretation of the agreement.

John Kimbell QC did not hesitate in his Judgment to deem all evidence in support of this position as inadmissible; it is the established position of English law of contract that statements made in pre-contractual negotiations are not admissible evidence to interpret the contract. The Judgment reiterates that given the presence of an entire agreement clause, any recourse to alleged mutual understanding is prohibited.


This case serves as a clear reminder that where the parties are sophisticated commercial entities and are in receipt of expert legal advice at the time of entry to the contract, the Courts remain unlikely to interfere. As John Kimbell QC states, ‘English law does not easily accept that people have made linguistic mistakes, especially in formal documents drawn up by sophisticated commercial parties with the assistance of commercial law firms on both sides’ (para 117).

It is therefore important to seek expert legal advice when drafting even the simplest of legal contracts as the mere fact that the parties have consulted their lawyers continues to be a clear indication of their commercial intent regardless of their commercial common sense.

Invicta Law’s Contracts experts can help you with all aspects of contracts law including legal principles of good faith, implied rationality and commercial common sense. Contact us on 03000 411993, email or download the team leaflet for more information.

Contents of this article are intended for general information purposes only and shall not be deemed to be, or constitute professional or legal advice.  Invicta Law cannot accept responsibility for any loss as a result of acts or omissions taken in respect of this article


Corporate and Commercial News

The Impact of Covid-19 Supplier Relief for Public Contracts

The Public/Private Joint Venture – Why Do They Succeed?

The Schrems II Decision: Is the Privacy Shield Dead?

Download our leaflet to find out more about our Corporate and Commercial services or get in touch with our team today on 03000 411100


Keep in touch

signup for our latest news and resources

By signing up you agree to receive information and news about Invicta Law services, for further information please review our privacy policy.