Let's look at the Chick-fil-A controversy from this summer. Some of Chick-fil-A's top management (IIRC it was their COO) made statements about how they support the traditional family and how gay marriage was an affront to their values. The only thing they did was donate to organizations that supported these values (admittedly, some of these organizations were pretty ridiculous). They did not bar gays from eating or working in their restaurants, nor did they say there was anything inherently wrong with homosexuality. They simply stated that the company operates and has a deep respect for the traditional family and Christian values (which isn't just posturing, they don't open on Sundays and the company's management has always been vocal about that).
Look at what happened to them. Keep in mind that all they did was say that gay marriage was against traditional family values. They did not bar gays from eating there, or actively discriminate against them. Within weeks of this happening, protests were staged at Chick-fil-A locations, gay couples publicly kissed at Chick-fil-A locations on August 3rd, 2012, and the Jim Henson company pulled their toys from Chick-fil-A kids meals, and announced it was ending their business relationship with Chick-fil-A. That being said, August 1st became a day where many Christians made a sort of pilgrimage to Chick-fil-A locations, to support family values. However, I doubt that the total hit on their image is made up for by one day of boosted sales.
See what happened here? A company made statements that the general public considered to be out of line and they showed their views accordingly. Chick-fil-A did not outwardly express contempt for homosexuals, only gay marriage itself. They did not forbid gays from eating or working there, they did not publicly state anything other than an issue with gay marriage from a Christian values perspective. Despite this, the general public still called out Chick-fil-A, made an effort to stop eating there, and their image has been forever tarnished because of it. All this for simply stating that they think gay marriage is wrong. Now imagine if instead of simply saying they oppose gay marriage because of their values, they said they want to keep gays out of their restaurants as employees or customers. Given the way the public reacted to the former, can you imagine the ramifications of the latter?
The issue with what happened to Chick-fil-A, and why I believe these "compassionate" laws are wrong, is demonstrated by Boston mayor Thomas Menino. Menino publicly stated that he wishes to do everything in his power to block a hypothetical Chick-fil-A franchise in Boston. All because they said they think marriage should be between a man and a woman. Chick-fil-A has never discriminated against gays as either customers or employees, yet the mayor of Boston felt that he should actively try to work against them setting up a franchise in Boston. Of course, there's very little he could practically do against the company, but the mere fact that a mayor of a city would claim such a thing shows me the root of the issue.
The slippery slope often is labelled as a fallacy, but from my observation it is not fallacious when applied to governments and law. The civil rights act was initially enacted to break down barriers and allow all to work, shop, and live in the same areas, regardless of race. It has been extended to include things like affirmative action, and laws based on "offensive" speech. This is the problem, give a government an inch to govern on the basis of social equality, and they won't stop.