My neighbors hedge grows over my fence by about 2 feet. They don't want to do anything about it and I am going to trim it. Can I go any distance into their property without a problem? Washington State

No, you can not step on, or get on their property to trim it without their permission.

You also can only trim it back to the property line, you can trim the part of the bush over your property, but not any of the bush on their property.

Does the fence set back from the property line or is the fence the property line. If the fence is the property line, you can trim anything that comes though the fence, but not reach over and trim anything on their property.

Have you talked to the neighbor ( and/or ) property owner if the house is a rental property.

This usually is covered in more detail by local ordinance, so check with your town, and even then it isn't often very well described, and ends up in small claims. But with hedges it's pretty straightforward: you trim all you want to the property line, and up an invisible vertical line. I'm not clear about what you mean about going 'any distance into their property.' That's something you ask them! They said they didn't want to do anything about the 2 feet hanging over your line, but that doesn't give you permission to go over it.