You can use backdoor to describe an action or process if you disapprove of it because you think it has been done in a secret, indirect, or dishonest way.
例句
He did the backdoor deals that allowed the government to get its budget through Parliament on time...他通過幕后交易使政府預算按時通過了議會批準。He brushed aside talk of greedy MPs voting themselves a backdoor pay rise.他沒有理會貪婪的下院議員們投票為他們自己悄悄加薪的傳聞。
N-SING
不正當的秘密途徑；后門
If you say that someone is doing something through or by the backdoor, you disapprove of them because they are doing it in a secret, indirect, or dishonest way.
例句
Dentists claim the Government is privatising dentistry through the back door.牙醫聲稱政府正通過暗箱操作將牙醫業私有化。