draw a line

[draw a line] or [draw the line] {v. phr.} 1. To think of as different.

The law in this country draws a line between murder and man slaughter.

Can you draw the line between a lie and a fib?

2. To set a limit to what will be done; say something cannot be done.

We would like to invite everybody to our party, but we have to draw a line somewhere.

- Often used with "at".

Mrs. Jones draws the line at permitting the children to play in their father's den.

People fighting for their freedom often do not draw the line at murder.