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		| Paper: | 
		Magnetic Fields in AGN | 
	 
	
		| Volume: | 
		144, Radio Emission from Galactic and Extragalactic Compact Sources, IAU Colloquium 164 | 
	 
	
		| Page: | 
		97 | 
	 
	
		| Authors: | 
		Wardle, J. F. C. | 
	 
	
	
		| Abstract: | 
		We review VLBI polarization results. In particular, we discuss the a) ``shock in jet paradigm'', b) the orientation of the magnetic field in jets as a function of optical identification, c) rotation measure and Faraday dispersion measurements as a probe of the narrow line region, and d) future directions of polarization observations. Results we emphasize are i) there is still a strong correlation between optical L/C ratio or EW and magnetic field orientation in the jets of blazars, even for high redshift weak-lined objects, ii) observed rotation measures are much smaller than expected from the properties of the NLR, except for some CSS sources. Also iii) a faint boundary layer or sheath (with a parallel magnetic field) has been observed around the jet of the weak-lined blazar 1055+018, and iv) circular polarization has been detected for the first time in the jets of 3C 84 and 3C 279. | 
	 
	
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