Implied terms of a contract of employment are like implied terms of a contract. The common law rule is that a term can be implied to a contract if a reasonable bystander overhearing the contract being made would have said, ‘of course it is obvious that they both meant to include that point – it goes without saying’ The theory is that the term was so obvious that the parties did not see the need to state it expressly.
Implied terms are those terms not expressed but necessary to give the transaction such business efficacy as the parties must have intended, see Luxor (Eastborne) Ltd v Cooper  AC 108 at 137
At common law, terms are implied to contracts of employment, not on the basis of intention of the parties but because such a term is a “necessary condition of the relation of master and man.” Lister v Ramsford Ice Co  AC 555 at 576
Terms that are too vague or unpredictable cannot be given business efficacy. There is no implied term for instance, that performance of the tasks assigned will always be in a manner the employee is habitually used by custom and practice,
A term can only be implied into a contract of employment if it would have existed at the time the contract was made. It cannot be used to override an express term, though may be used to qualify or explain it.
There is a broad range of implied terms that depends ultimately on the nature of the employment contract and the specific facts of each case.
Mumende v Nyali Golf & Country Club  KLR13 Gachuhi, JA noted that, “it is an implied term of employment that an employer will make the conditions of employment to his employee absolutely safe and will not expose his employees to any danger to avoid any negligence, but will not be responsible of the employee’s own negligence in execution of such employment.”
There is no implied term that the barring any dismissal or compulsory retirement, a contract of employment is to persist indefinitely till retirement, see Chase v BBK; Murgani v KRA  eKLR; East African Airways –v- Knight (1975) EA 165
There is an implied term of mutual trust and confidence