Not always, but most of the time.
LEDs are susceptible to current and voltage spikes simply due to their low operating voltage and minimal current demand. If an external heavy load is applied to an electric circuit which is also running a LED light, the dips in voltage and current can seriously affect the lifetime of an unprotected LED chip. Examples include swimming pool pumps and large refrigerators, which can cause premature failure of incandescents and halogens too.
To alleviate this problem, constant current LED drivers are used, incorporating an integrated circuit which senses and compensates for voltage variations.
Many of Lighting Mattersí LED lamps have this technology built in, and can withstand a wider range of input power than even the typical halogen or incandescent. However, if you are looking to change over your 12V halogen downlights for LEDs, we suggest either swap to GU10 240V fittings, or use a suitable LED driver due to the complexity of halogen transformers and fluorescent ballasts.