walk a fine line between (something)

To navigate or strike a balance between two sides, positions, or approaches to something, especially when trying to avoid one of them. The film walks a fine line between parody and homage. As a new parent, you have to walk a fine line between looking out for your child's welfare and being overprotective.

If someone walks a fine line between two activities or situations, or treads a fine line between them, what they are doing is acceptable, but they are very close to the point at which it would become unacceptable. At present we are walking a very fine line between getting away with it and having a very serious problem. The American will tread a fine line between freshness and a shortage of match fitness. Note: You can also say that you walk or tread a thin line between two things or that you walk or tread a narrow line between them. He must tread a narrow line between investigation of his party's mistakes and charges of disloyalty. Compare with a fine line between something.