Legal opportunism is a wide area of human activity, which refers generally to a type of abuse of the proper intention of legal arrangements (the "spirit of the law" as distinguished from the letter of the law). More specifically, it refers to deliberately manipulating legal arrangements for purposes they were not meant for, guided by self-interested motives.
Usually, legal opportunism is understood to occur legally: it is itself not necessarily a "crime" (a violation of the law or an unlawful act), but it could be considered "immoral" ("there ought to be a law against it"). The general effect of legal opportunism, if it really occurs, is that it discredits the rule of law or destroys the legitimacy of particular legal rules in the eyes of the people affected by them. Inversely, if people perceive a legal framework as arbitrary, obstructive or irrelevant, they are tempted to search for opportunities to find ways "around the law", without formally breaking the law.
Typical of legal opportunists is that they accept or approve of the application of legal rules when it suits their own interest but reject or disapprove of the application when the rules are against their interest (or if taking self-interested action would mean breaking the law). The law should serve them, and not the other way around; or, there is "one rule for them, and another rule for other people."
Often, legal opportunism is enabled because a rule must be interpreted in order to apply it (i.e., how exactly it applies in the given situation is not self-evident or obvious), where the chosen interpretation is precisely the one that favours one's self-interest. If a situation is governed by many different and possibly conflicting rules, some choices may be possible in deciding exactly which rule applies. The opportunist then picks the option that suits himself. It may be that the original circumstances a rule was intended for have changed, so that the rule in reality gains a different significance from what it originally had—creating an ambiguity that some could exploit opportunistically.
Since there are many dubious ways to manipulate the applicability of legal rules and procedures for selfish purposes, a general definition of legal opportunism (one which covers all cases) is exceptionally difficult. All the types of opportunism mentioned in this article may appear in a specifically legal form. Legal opportunism can involve practices such as the following:
- Making or changing laws not for the good of the country as a whole, but to benefit a particular interest group in the country.
- Making or changing laws, primarily to benefit the position of the law-makers themselves.
- Applying or referring to legal procedures not for the sake of obtaining justice (or so that justice is served), but mainly with the aim of making money out of it, or promote one’s own position, or to place competitors at a disadvantage.
- Exploiting legal loopholes or ambiguities for personal gain or to the advantage of a particular organization.
- In some cases, "tinkering with" bad legislation, formalities or rulings "after the fact": after it is proved that a legal rule previously established is definitely unjust, wrong, inapplicable, mistaken etc. or incriminating someone using a new rule adopted only after the alleged crime was committed.
- Deliberately "embellishing" selective evidence relevant to a legal situation, to benefit one's own position, in ways that are not strictly illegal.
- Trying to sway legal opinion about a case by using arguments or utterances that appeal to the audience, but have substantively nothing to do with the case at hand.
- "Cherry-picking" pieces of evidence, rules or precedents to construct a justification for the policy option that favour's one's own interest.
It should be noted, that in an adversarial system all kinds of tactics can be legitimately used by lawyers in a self-interested way to help them win their case, without being illegal. Therefore, to prove "legal opportunism" as a specific form of abuse of the legal process, for some selfish purpose, can be quite a challenge.
Normally, a modern system of law assumes, that citizens as legal subjects all have the same legal status before the law, and that the law is applied uniformly to all citizens in the same way, under the same circumstances. However,
- There can always be differences about the interpretation of the exact meaning, purpose, intent and application of laws in particular situations.
- Rules can be constructed in ways that are formally the same for everyone but really advantage some and disadvantage others.
- There may be new and novel situations where the law's applicability is unclear.
- The combination of different systems of rules can create unforeseen consequences or uncertainty about how to apply the rules, or about which rule applies in a given case.
- A legal rule, although enacted in a statute, may state or imply a principle that is impossible to enforce systematically for some reason, with the effect that people follow their own interpretation in a self-interested way without penalty.
All of these make possible an opportunist exploitation of legal frameworks by legal subjects, for self-interested motives without necessarily violating any legal principle, though the intention of the law (the real purpose or aim that inspired it) is negated.
- Joanna Brylak, "Legal awareness and access to law". University of Warsaw, c. 2007, p. 5. 
- "It should be no surprise that when rich men take control of the government, they pass laws that are favorable to themselves. The surprise is that those who are not rich vote for such people, even though they should know from bitter experience that the rich will continue to rip off the rest of us. Perhaps the reason is that rich men are very clever at covering up what they do." - Andrew Greeley, "U.S. should try to reduce income disparity". Chicago Sun-Times, 18 February 2001.