The purpose of this paper is to present a new method to de- sign exact geometric predicates in algorithms dealing with curved objects such as circular arcs. We focus on the com- parison of the abscissae of two intersection points of circle arcs, which is known to be a difficult predicate involved in the computation of arrangements of circle arcs. We present an algorithm for deciding the x-order of intersections from the signs of the coefficients of a polynomial, obtained by a general approach based on resultants. This method allows the use of efficient arithmetic and filtering techniques lead- ing to fast implementation as shown by the experimental results.