An LM317 is often used as a current limiter for a power supply but you must allow about 3V across it for normal operation which increases the required input voltage and dissipation for a given current and load voltage. This circuit is a little more complex but it can generate a voltage drop of less than a volt (about one base-emitter voltage drop) during normal operation depending upon the current limit range.
The circuit below uses a P-MOSFET as the current limit element and a PNP to detect...