Can I restrict access on a shared board?

[Delwyn I Jones]

Is there a method by which I can designate a card to a workspace member and ensure only that member can edit the card?

I need a member, not an observer, but want to restrict card access/changes to a single member on a multi member board.

For example: I designate a card called "project 1" to "Joe Bloggs" is there a method/rule to ensure that "Ann Other" or other (non Admin0 board members are unable to make changes to "Joe's" card?

I am a Premium subscriber and have administrative privileges of our workspace. 

[Daydreamer Mike]

You can use automation to undo certain things that a member does.

This example is where where you only want a certain person to be able to move a card....You could do the same for dates, custom fields, labels etc...