i. It safeguards an individual’s expectations in the face of a change of policy by an authority.
Dr. Robert Thomas, Professor of Public Law at the University of Manchester, provided a succinct summary of the principle/doctrine of legitimate expectation:
“The principle means that expectations raised as a result of administrative conduct may have legal consequences … The principle therefore concerns the degree to which an individual’s expectations may be safeguarded in the face of a change of policy which tends to undermine them.”
In Law Pang Ching & Ors v Tawau Municipal Council  3 MLJ 452, Abu Samah JCA and Raus Sharif JCA (as their Lordships then were) held:
“A common trait in all these cases is that the aggrieved parties stand in direct relationship — without any go-between — with the decision makers. The expectation arises where a person responsible for taking a decision has induced in someone who may be affected by the decision a reasonable expectation that he will receive or retain a benefit or that he will be granted a hearing before the decision is taken. See De Smith, Woolf and Jowell, Judicial Review of Administrative Action, (5th Ed) paras 8–037.”
ii. It arises where there is an express promise by the authority, or where there exists a regular practice that one may reasonably expect would continue.
Lord Fraser in the seminal case of Council of Civil Service Union v. Minister for the Civil Service  AC 374 held:
“Legitimate, or reasonable, expectation may arise either from an express promise given on behalf of a public authority or from the existence of a regular practice which the claimant can reasonably expect to continue.”
In Zakiah bte Ishak v Majlis Daerah Hulu Selangor Darul Ehsan  6 MLJ 517, the Court of Appeal similarly decided that “… In law for legitimate expectation to arise there must be evidence of a promise or undertaking made by the respondent to that effect.”
iii. It is based on the duty to act fairly as a necessary element of good governance or good administration.
The Court of Appeal in Mayland Valiant Sdn Bhd v Majlis Perbandaran Subang Jaya  4 MLJ 685 remarked that the principle/doctrine of legitimate expectation is:
“… based on the duty to act fairly as a necessary element of good governance or good administration (see W Wade & C Forsyth, Administrative Law (8th Ed, Oxford University Press: Oxford, 2000) pp 494-495. The Privy Council in the leading case of A-G of Hong Kong v Ng Yuen Shiu  2 AC 629 held, in quashing a deportation order, that ‘when a public authority has promised to follow a certain procedure, it is in the interest of good administration that it should act fairly and should implement its promise, so long as the implementation does not interfere with its statutory duty’.”
iv. It is a relevant consideration which must be taken into consideration in the exercise of an authority’s discretion.
In De Smith, Woolf and Jowell’s Judicial Review of Administrative Action (5th Ed), the learned authors point out that:
“Although free to alter its policy, the authority is by no means free to ignore the existence of a legitimate expectation. Now that legitimate expectation has been accepted in Law as an interest worthy of protection, its existence becomes a relevant consideration which must be taken into consideration in the exercise of a discretion. It is placed on the scale and must be properly weighed.
It is at this point that the fact that the promissee relied on the expectation to his detriment may be relevant. Detrimental reliance will add to the weight of the legitimate expectation. It may be overridden by competing public interest, but the greater the evident detriment to the promissee, the greater the countervailing weight of the public interest in order to override an expectation that is held to be legitimate.”
The above extract was cited by the Federal Court in Majlis Perbandaran Pulau Pinang v Syarikat Kerjasama-sama Serbaguna Sg Gelugor Dengan Tanggungan  3 MLJ 1.
v. It is only applicable in public law matters.
The Court of Appeal in GPQ Sdn Bhd v Constant View Sdn Bhd  6 MLJ 728 held the following:
“On the issue of legitimate expectation we agree with the point raised by the defendant that the doctrine of legitimate expectation is only applicable in public law and not to private law matters.”
This position was affirmed by a subsequent Court of Appeal panel in Daud bin Arshad & Ors (representing 61 settlers/participants of FELCRA Gugusan Sungai Ara, Mukim Ulu Sungai Sedili, Daerah Kota Tinggi, Johor) v FELCRA Bhd  2 MLJ 33 (“Daud bin Arshad”).
Tengku Maimun JCA (as Her Ladyship then was), in delivering the judgment of the court in Daud bin Arshad, held:
“As for legitimate expectation, the doctrine was only applicable to public law matters and not to private law matters (see GPQ Sdn Bhd v Constant View Sdn Bhd  6 MLJ 728;  4 MLRA 483. See also Darahman bin Ibrahim & Ors v Majlis Mesyuarat Kerajaan Negeri Perlis & Ors  4 MLJ 309;  1 MLRA 411).”
vi. It may be overridden by competing public interest.
In De Smith, Woolf and Jowell’s Judicial Review of Administrative Action (5th Ed), the learned authors note that the principle/doctrine of legitimate expectation:
“… may be overridden by competing public interest, but the greater the evident detriment to the promissee, the greater the countervailing weight of the public interest in order to override an expectation that is held to be legitimate.”
The Court of Appeal in Law Pang Ching & Ors v Tawau Municipal Council  3 MLJ 452 alluded to the possibility of a overriding public interest negating a legitimate expectation:
“All that needs to be added is that in the present instance there is no overriding public interest that calls for a negation of the legitimate expectation created in the appellants by the representation earlier adverted to.”
vii. It is likely not applicable if the authority acting upon it would invoke a breach of statute.
In Government of the State of Negeri Sembilan & Anor v Yap Chong Lan & 12 Ors; Lesco Development Corporation Sdn Bhd v Yap Chong Lan & 12 Ors  2 MLJ 123, the Respondents claimed to have acquired an equitable right or interest to remain on the respective lots allocated to them by virtue of the Collector of Land Revenue giving them permission to occupy State land. 
The Federal Court held that:
“… in the light of the statutory provisions we have referred to and the authorities we have discussed it would appear that the equity sought to be raised by the respondents would establish against the State Authority rights in respect of State land which it is prevented by statute from creating other than in the prescribed manner.”
viii. It cannot override express statutory powers vested in an authority.
The Federal Court in North East Plantations Sdn Bhd v Pentadbir Tanah Daerah Dungun & Satu Lagi  supp MLJ 293 agreed with the majority decision of the Court of Appeal and held the following:
“… keputusan majoriti Mahkamah Rayuan adalah tepat apabila dinyatakan ‘Whether or not the doctrine of legitimate expectation applies depends on the facts of each case, it cannot and should not override the express statutory power vested in the State Authority’.”
In a recent decision, the Court of Appeal in Pentadbir Tanah dan Daerah Petaling & Ors v Bandar Utama City Corporation Sdn Bhd (dahulunya dikenali sebagai Damansara Jaya Sdn Bhd) & Anor and another appeal  MLJU 222 held that:
“… the doctrine of legitimate expectation cannot be extended to bar the powers of the State Authority to acquire land under the LAA 1960.”