Digital Logic current flow IFF current in different circuit
I would use a tri state buffer.

Here is an example of a real-world part: from texas instruments

The part I have linked is active low, however. The current flowing in this case would be the leakage current into/out of the control pin. This current can be thought of as controlling the 'path' for the main current to flow through.



Additional:
Wikipedia entry on 3-state logic

The high impedance output is the state that 'blocks' current.