  Aims. We use high-resolution spectropolarimetric observations in the Ca ii
8542 A line obtained with the SST to study the magnetic field in solar
spicules. Methods. The equations that result from the application of the Weak
Field Approximation (WFA) to the radiative transfer equations are used to infer
the LOS component of the magnetic field (BLOS). Two restrictive conditions are
imposed on the Stokes I and V profiles at each pixel before they can be used in
a Bayesian inversion to compute its BLOS. Results. The LOS magnetic field
component has been inferred in six data sets totalling 448 spectral scans in
the Ca ii 8542 A line and containing both active region and quiet Sun areas,
with values of hundreds of G being abundantly inferred. There seems to be no
difference, from the statistical point of view, between the magnetic field
strength of spicules in the quiet Sun or near an active region. On the other
hand, the BLOS distributions present smaller values on the disk than off-limb,
a fact that can be explained by the effect of superposition on the chromosphere
of on-disk structures. We find that spicules in the vicinity of a sunspot have
a magnetic field polarity (i.e. north or south) equal to that of the sunspot.
This paper also contains an analysis of the effect of off-limb overlapping
structures on the observed Stokes I and V parameters and the BLOS obtained from
the WFA. It is found that this value is equal to or smaller than the largest
LOS magnetic field components of the two structures. In addition, using random
BLOS, Doppler velocities and line intensities of these two structures leads in
~ 50% of the cases to Stokes I and V parameters unsuitable to be used with the
WFA. Conclusions. Our results present a scarcity of LOS magnetic field
components smaller than some 50 G, which must not be taken as evidence against
the existence of these magnetic field strengths in spicules.
