I'm specifically referring to a someone which one shouldn't have, from the speaker's perspective.
For example:
"We shouldn't allow the government to get comfortable with this ?????? power."
Where the '?' describes the fact that the power shouldn't be theirs or is unfounded. (1 word)
I think the word I'm looking for is closely synonymous with 'undeserving', as I don't think 'undeserving' is grammatically correct in this context...
... with this arrogated power.
All dictionaries will have a definition similar to "taken or claimed without right or justification".
Unmerited is a good match for your meaning:
not adequately earned or deserved : not merited
To focus on shouldn't I think usurped is appropriate [Cambridge Dictionary usurp]:
to take control of a position of power, especially without having the right to
We shouldn't allow the government to get comfortable with this usurped power.
Less obscure could be illegitimate Cambridge Dictionary:
not legal or fair:
The rebels regard the official parliament as illegitimate.
Unwarranted would work in this context. Warranted means (OED)
Allowed by law or authority; approved, justified, sanctioned.
and so unwarranted would be something that not approved, justified, or sanctioned.
In a political register, assumed works:
assume: seize; usurp
- assume control
(In other contexts, assumed has of course other default meanings.)
undeserving is wrong because it would describe how the power acts. But the same concept can be applied correctly with undeserved, which refers to how the power was achieved -- it didn't deserve it. Similarly, if someone receives praise for something they didn't actually do, we would say they're "undeserved compliments".
Ill-gotten is a term indicating that something has been gained through illegal or unfair means. It implies not just that the thing in question should not be held by the person who has it, but also that they did something unscrupulous to get it.
A less specific term, which might be more accessible to a wider audience, is purloined.
purloin (v): to appropriate wrongfully and often by a breach of trust (Merriam-Webster.com)1
"legislators from the rural prison counties often use this purloined power to vote against the interests of the urban communities from which prison inmates most typically come. " -- Prisoners of the Census (about prisoners counting towards the Census power of the locations where they are imprisoned without being able to vote.)
"This meritless lawsuit is designed to rally progressives to defend California’s purloined power to regulate fuel economy." -- Fuel Economy: California (about claims of inappropriate government lobbying activity.)
One legal term is
ultra vires
adjectivebeyond the legal power or authority of the person performing an action
The company's actions in entering into a contract with him were ultra vires, and therefore the contract was void.
A shareholder could restrain the company from undertaking ultra vires activities.
From Cambridge Dictionary.
The sentence could be
We shouldn't allow the government to get comfortable using this ultra vires power.
Or more concisely
We shouldn't allow the government to use this ultra vires power.
There are several good answers here, but I'll add misappropriated and its lightly harsher cousin malappropriated, which both mean to take control of something inappropriately.
Misappropriated means that a party was in a position of trust to manage or control something, but then abused that trust by exceeding the granted authority, usually by directing resources away from their intended target for personal gain or benefit, or by exceeding the amount of usage allowed.
Misappropriated is often used in financial terms to refer to someone making use of funds in a way that they are not supposed to, but it can also be used to refer to misuse of other things, such as property, materials, or as in this example, power.
When the rule of law has been ignored on a political whim, we feel it reverberate in ways that seem to shake us to the core. Misappropriated power thrives where rule of law ends.
Malappropriated has a slightly stronger implication of deliberate malice, but both indicate dishonesty and a violation of trust.
Unchecked is frequently used in your context in the sense of "growing more than deserved".
"We shouldn't allow the government to get comfortable with this unchecked power."
Collins:
unchecked ADJECTIVE
If something harmful or undesirable is left unchecked, nobody controls it or prevents it from growing or developing.This provision gives the president total and unchecked power.
I think we are all agreed that one should not steal, and that stealing is a way of coming into unauthorised possession of something:
"We shouldn't allow the government to get comfortable with this kleptocratic power."
OED
Etymology: klepto- Forming words in which it has the sense ‘theft, thieving’, as kleptocracy, kleptomania. Plus -cracy: From French ‑cratie < post-classical Latin ‑cratia < Greek κρατία (in compounds) power, rule, < κράτος strength, might, rule, authority.
kleptocratic Of, designating, or relating to a kleptocracy.
2001 After a decade of robber baron capitalism that burned Western investors, these bosses now say that kleptocratic practices proved a dead end for a country with an annual gross domestic product of $300 billion. Business Week 12 November 70/1
kleptocracy: A ruling body or order of thieves. Also, government by thieves; a nation ruled by this kind of government.
