Word for biased interpretation of the law?

Solution 1:

The answer is what Black's Law Dictionary terms Color of Law.

Here is the definition from the abridged fifth addition: "The appearance or semblance without the substance of legal right. Misuse of power, possessed by virtue of state law and made possible only because wrongdoer is clothed with authority of state."

Solution 2:

I think abuse may be used in the context described:

An unjust or wrongful practice: a government that commits abuses against its citizens.

Solution 3:

There is the sarcastic usage (misusage?) of the phrase the golden rule. In this context, it is said to mean

He who has the gold rules (or makes the rules).

In stark contrast, the classic concept of the golden rule posits

One should treat others as one would like others to treat oneself.

This nobler concept is accepted as a guiding principle in many religions and social traditions.

There is a common political structure known as an oligarchy

a government in which a small group exercises control especially for corrupt and selfish purposes; also : a group exercising such control

While control or influence by a powerful elite does not necessarily imply corruption and selfserving behavior, it is often the case.

Solution 4:

I believe you are specifically asking for legal opportunism:

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.

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.

As a single word, you can use manipulation or exploitation (or their verb forms).