-- Well, my much longer post got eaten and I don't want to retype my examples So here's an executive summary:

* SR laser weapons (Arsenal, p. 41) have come a long way since Fields of Fire and are no longer expensive toys with laughable bang-for-buck when faced with armor that would otherwise be "out of their league" size-wise. They are not cost effective against street-level foes wearing stuff like armor jackets (especially if you have APDS for your Predator). And their range restrictions can be ruinous - medium range (11m) in a light drizzle (Seattle weather) and the Redline is reduced to 3P damage and is at a -2 dice penalty right off the top. But they have a niche, which is more then I can say for them in the old days.

* However, I note that Shadowrun, for all the additions of acoustic heterodyning sonic beams and radiofrequency weapons, doesn't have blinding/dazzling laser weapons! This is a tragedy that proves the terrorists have already won, my friends. I say enough is enough and we steal ... I mean borrow ... a mechanic from GURPS Ultra-Tech where beam weapons can use alternate dazzling and blinding modes (pp. UT113-114). I like to spell out my thinking process, so here goes (with page references - A = Arsenal, UT = Ultra-Tech, SR = Shadowrun 4e):

ASSUMPTIONS
* SR4 lacks blinding laser weapons (e.g. a weapon analogous to the ZM-87).
* The closest mechanics I can find are for snow blindness (i.e. -1 glare penalty, p. A164); flash grenade (pp. A36-37); flash-pak (p. SR313). Flare compension reduces these penalties by 2.
* The camera neutralizer is actually a blinding laser in disguise (p. A59).
* A parallel mechanic we can borrow could be the sonic beam rifle (p. A39).

RULES
* So, possible dazzle mode for laser weapons:

Dazzle Lasers
High-energy laser weapons, such as those described in Arsenal (p. 40), may be used in a dazzle mode. Anyone facing the laser recieves a penalty to attack tests equal to the DV of the beam due to the intense glare. Flare compensation reduces this modifier by 2. This modifier fades away at the rate of 1 point per Combat Turn. Dazzle shots use negligible power. It requires a Simple Action to switch between normal and dazzle firing modes.

FUTURE WORK
* Still thinking about actual blinding laser rules, probably use the shotgun spread rules with a Body resisted attack against the DV of the beam where failure equals temporary disorientation and blindness, with a glitch making it permanent. Using weapon DV has the handy game balancing mechanic of making them rather anemic at significant ranges, so unless you use the naval laser you're not going to be frying everyone in Seattle's optics on a whim.

No need for blinding lasers...
...Just use commonly available and relatively cheap laser pointers.

There've been several cases of aircraft pilots being blinded by them and the more powerful laser pointers are now restricted items in Australia.

Truly, fact is weirder than fiction.

Considering that there's a whole development cycle for "humanitarian" blinding lasers [humanitarian because they cause short term blindness rather than injury/death], there should definitely be something for them in the rules...
...But blinding your opponents obviously isn't cool enough

I have a few suggestions. I would think it'd have to incur a penalty to tests other than just attack tests if the weapon's effects actually take a bit to fade away; clearly it's doing something to be more debilitating than a simple flash-pak, in that case, and a penalty to Perceptions tests seems consistent. Second, if it's going to affect everyone facing it for no ammunition cost, then I think you should cap the penalty at the -6 full darkness threshold just like any other visual interference (-4 if you have Flare Compensation); hardly a big deal since the nastiest man portable versions only hit 7 and 9 DV anyway, but hey, every little bit counts, especially if you're using this thing to help your chummers face down a whole squad of bad guys. If dazzle mode is causing disorientation beyond that threshold, I think you'll need to put in some way to stage it down via a willpower or perception test of some sort.

-- Honestly this sounds a bit fishy, in SR terms it was probably a glare modifier and people over-reacted.

-- Actually, blinding laser weapons are high on the list of weapons most humanitarian groups would like to see banned (and they basically are already - they are restricted under the 1995 United Nations Protocol on Blinding Laser Weapons (which is why systems like the ZM-87 were instantly reclassed as "laser rangefinders.") Most of NATO is quickly replacing their armored vehicle laser rangefinders with "eye safe" models due to concerns that they can (and were) used in a dazzling manner.
-- The military has a rather .... broad ... definition of "nonlethal" though, which is why you see things like the ADS

-- I'm not sure if would be more debilitating than a flash-pak, in SR terms (the general effect being "you can't see"). I do concede that blindness would have additional effects that are not really laid out in SR4.

-- I would agree, but it seems like a special case exemption that complicates the rules. If pushed, you could justify the additional penalties as being due to retinal burning and disorientation from pain.

Well, here's the thing though, if it goes beyond simple blindness, it opens the door a bit as to whether it's a purely visual phenomena or not. Making people "extra" blind is a bit problematic, since you could concievably start stacking penalties via zapping the guys with the dazzle your first pass and then tossing the smoke grenade the second pass. The dazzle would have hit the guys full force and since it takes a bit for the effect to completely wear off some players might try arguing for both effects. Sorry if I seem pushy, I just always try to think like a rules lawyer when looking at these things for the sake of keeping the end result as simple as possible. Plus, my players like to break everything they touch, so the line "You can't get any blinder, Stevie" has become something of an article of faith at my table when it comes to blindness effects and the -6 total darkness threshold.

You can justify further penalties beyond visual.

It's a proven fact that you can use light to make people feel nauseous. Try aiming a gun when you can barely see anything, your balance is screwed up, and you feel nauseous.

Light can cause all those conditions and at the same time.

I know. Strobe lights can even trigger photosensitive epilepsy. That said, my primary concern is simplicity and consistency with rules that are already in the game. While visual modifiers already hamper the effectiveness of laser attacks, that balancing factor only really comes into play if the modifiers are present when the weapon is used in the first place, which is a bit problematic because the dazzle effect lingers and because Shadowrun combats can take a notoriously short number of rounds plus contains several visual penalizers which can be used more or less on demand. I guess I just think an explicit limiting factor that keeps within the spirit of already existing rules hits me as appropriate.