Is there an idiom for, " Making decision all by yourself without involving or consulting others and expect them to accept it"?

I know there are some idioms meaning that you do a job alone or sth. But what I'm looking for is the one in which a person is supposed to consult with others before making final decision but he just does it all by himself and think that the others will accept the decision and all is done!

For example: When she realized that he had made all the decisions before asking for her opinion she lost her temper and said, "Hey, you just [THE IDIOM]? Don't you think we should all have a say in this?"

Solution 1:

He made the decision unilaterally.

He made the decision by fiat.

Solution 2:

Taking Liberty is a good choice if you are implying about doing something without asking.

I took the liberty and checked the editorial manager of Renie