Glossary
Reasonable endeavours
reasonable endeavoursReasonable endeavours is a duty to take the steps a reasonable person in that position would take, without sacrificing the party's own commercial interests. Best endeavours is heavier. All reasonable endeavours sits in between. Jet2.com Ltd v Blackpool Airport Ltd [2012] EWCA Civ 417 is a leading modern case. Name the objective and any budget or time cap.More in the glossary is a duty to take the steps a reasonable person in that position would take, without sacrificing the party's own commercial interests. Best endeavours is heavier. All reasonable endeavours sits in between. Jet2.com Ltd v Blackpool Airport Ltd [2012] EWCA Civ 417 is a leading modern case. Name the objective and any budget or time cap.
Last updated 28 October 2026
English drafts use a ladder: reasonable, all reasonable, best. Reasonable endeavours means you try, you spend what is sensible, and you may prefer your own commercial interest. Best endeavours means you take all the steps you can that do not ruin you. Rhodia International Holdings v Huntsman [2007] EWHC 292 (Comm) is often cited on the difference. Jet2.com shows that even an endeavours clause can force a party to act against a short-term interest if the objective was the point of the deal.
We pick one phrase and define the objective. Lex will not write “best endeavours to launch, whatever it costs.” If the thing that matters is a date, use the date, or time is of the essence. Endeavours is for things you cannot absolutely promise: a third-party licenceA licence is permission to use work in an agreed way, without taking ownership away from the person who made it.More in the glossary, a planning consent, a platform API staying up.
How do they differ from best endeavours?
Best endeavours is the top of the ladder. It can require expenditure and action against a short-term interest. Reasonable endeavours lets you weigh cost and your own commercial position. Do not use “best” because it sounds keener; use it because you mean the heavier duty.
Are all reasonable endeavours stricter?
Yes. The usual reading is that the party must take all reasonable paths, not just one, but still short of best endeavours. Because the case law is fact-heavy, define the steps: apply by a date, spend up to a named sum, escalate once to a named person. A defined list beats a fight about the adjective.
Should we define the steps?
Always. “Reasonable endeavours to obtain the licence” plus “including applying to X by [date] and paying official fees up to £Y” is a clause you can audit. An undefined endeavours promise is how a later court reconstructs a year of emails.
What if the objective becomes impossible?
Endeavours does not require the impossible. If a third party refuses, you have usually discharged a reasonable-endeavours duty by asking, escalating once and recording the refusal. If the whole job then cannot proceed, that is force majeure or a condition precedent, not a breach of endeavours.
A worked example
A website build needs a third-party app-store listing. The studio promises reasonable endeavours to obtain it, including submitting by 1 June and paying official fees up to £400. The store refuses on policy grounds. The studio records the refusal and stops. That is a discharged endeavours duty. A “best endeavours to launch on 1 June” line, with no cap, would have been the wrong tool — the launch date should have been a milestone, not an endeavours promise.
How it shows up in a contract
Sample wording · our own drafting
The Supplier will use reasonable endeavours to [obtain the third-party approval], including the steps in Schedule 2. The Supplier is not required to sacrifice its own commercial interests or to spend more than [£X]. This is not a best-endeavours obligation and is not a guarantee of the result.
In Plain English
We will take the sensible steps listed to try to get the approval. We will not wreck our own business to do it, and we will not spend more than the named sum. This is not a promise that the approval will land.
Common mistakes
- Writing “best endeavours” because it sounds keen, then being asked to spend without a cap.
- Leaving the objective and the steps undefined.
- Using endeavours for a date that should have been a milestoneA milestone is a defined point in a project, often tied to a deliverable and a payment.More in the glossary or time is of the essence.
- Treating a refused third-party consent as a breach of a reasonable-endeavours clause you had already performed.
Frequently asked questions
What are reasonable endeavours?
A duty to take the steps a reasonable person in that position would take, without sacrificing your own commercial interests. Name the objective and any spend cap.
How do they differ from best endeavours?
Best endeavours is heavier and can require action against a short-term interest. Reasonable endeavours lets you weigh cost. Jet2.com [2012] EWCA Civ 417 is a modern case.
Are all reasonable endeavours stricter?
Yes — usually all reasonable paths, not just one, but still short of best. Define the steps so you are not arguing about the adjective.
Should we define the steps?
Always. A list you can audit beats an undefined promise. See /glossary/time is of the essence“Time is of the essence” makes a deadline a condition of the contract. In England and Wales a party who misses that deadline is then in breach of a condition, so the other side can terminate and claim damages even if the delay is short.More in the glossary if what you actually need is a date.
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The legal wording governsLast reviewed 28 October 2026Pending lawyer review