  We exhibit an obstruction for groups with Property (T) to act on the real
line by bi-Lipschitz homeomorphisms. This condition is expressed in terms of
the Lipschitz constants and the Kazhdan constants associated to finite,
generating subsets. As a corollary, we obtain an upper bound for the Kazhdan
constants of orderable groups. Our main tool is the Koopman representation
associated to the action
$\operatorname{BiLip}_+(\mathbb{R})\curvearrowright\mathbb{R}$.
