def _can_use_proxy(settings, authority):
    """
    Return `True` if an annotation can be shown via the proxy service.

    This currently only considers the authority but in future it could also
    incorporate checks for whether the target page embeds Hypothesis.

    :param settings: App settings dict
    :param authority: Authority of annotation's user
    """

    # The proxy service can only be used with pages that use first party
    # accounts, because third-party accounts require the host page to supply
    # login information to the client, which in turn relies on the user's cookie
    # session and therefore does not work properly through the proxy.
    return settings["hypothesis_authority"] == authority