IMPLICATIONS OF THE WARP 5 SPEED LIMIT
A temporary upper limit for warp speed travel was established by the Federation Council, ref. [TNG: Force of Nature], after speeds exceeding warp factor 5 were found to cause dangerous damage to the space-time continuum. This speed limit was abandoned a couple of years later when it is assumed that newer Federation starships, such as USS Voyager and the new USS Defiant) are fitted with improved and environmentally-friendly warp drive systems which do not cause damage to the spatial continuum. Voyager's fold-up nacelles are inferred as contributing to those improvements. But Federation Starfleet deals with numerous species which are not subject to the warp 5 speed limit, nor which are constrained to install environmentally-friendly warp drives. In the Delta Quadrant, Voyager is the only Starfleet vessel (apart from the Equinox which before long had installed an enhanced warp drive contrary to Federation principles). In the galactic population of warp-capable species, how many of these have similar environmental principles as Starfleet? Without modified warp drives, a species that attains above warp factor 5, is damaging the space-time continuum, yet the Prime Directive of [TNG] onwards forbids interference. Does that mean Starfleet cannot say, "hey, your warp drives are damaging space-time continuum, let us modify your engines?" It is doubtful that the Prime Directive permits such interference unless a species either requests specific aid in this area or appears willing to accept the advice. It is likely that species capable of high-speed warp factors would or could detect the damage to the space-time continuum. Those who cared would alter their warp drive systems. But many would not. Candidates for the "would not" are the Malon (ref. [#95 Night]) and the Jelinians (ref. [#161 The Void]). Therefore, it seems that environmental morals hold no influence with regard to the Prime Directive.
