Ok I'll bite.
For starters, these laws are being introduced and passed by a government which was elected with 39% of the popular vote during an election where only 61% of eligible voters actually showed up.
This government which does not have a majority of support from Canadians also prorogued parliament to avoid defeat through a democratic process and were later found in contempt of parliament.
The same government engaged in election fraud and used underhanded legislation to cover their tracks and prevent future investigations into their misdeeds, past or future.
The same government signed in secret a binding 31-year-long deal with a military dictatorship which shares none of the values that Canada traditionally espoused.
They muzzled scientists and cut funding to research which yielded evidence of major downsides to their "golden egg" development plans for Alberta's oil resources.
They opened the door to mass immigration from aforementioned military dictatorship as well as major capital flight through millionaire investors which has distorted the largest housing markets in Canada.
They presided over a massive temporary foreign worker program despite widespread youth unemployment and underemployment.
They engaged in illegal spying on Canadians through CSE and diverted massive amounts of public funds to expanding our intelligence groups into P3 super-agencies.
They approved of major sales of critical energy infrastructure to foreign competition with no stake in Canada's social sphere.
They approved of an arms deal to an authoritarian backwater country that uses capital and corporal punishment in the suppression of democracy and women's rights.
They lied about our involvement in Iraq and have pushed us into a major ethnic/sectarian conflict that won't be resolved by any of the efforts we could afford to provide.
They pass almost every piece of legislation with minimal debate and to coincide with media events such that the public is mostly unaware of the major changes in our legal landscape that are occurring.
They scoff at the unconstitutionality of some of their legislation and are more than willing to waste time and taxpayer dollars on fighting the SCC, including accusing the Chief Justice of the SCC of malfeasance.
And now they are expanding our spy agencies beyond anything seen before in Canadian history, despite widespread opposition by Canadians and an unimpressive track record with the economy which is the central pillar upon which their government has gained power.
But forget about that - it's all ad-hominem right? What if a thousand monkeys banging on a typewriter wrote the legislation?
Let's address that:
Data is fickle. It doesn't stay where you want it to no matter how badly you try. Information that is gathered on a person or group and is stored remains there forever - to be used not only by those that come later and might have nefarious motivations, but foreign governments which seek a competitive edge against Canadian businesses.
With known breaches of security of both Canadian intelligence systems and American ones by foreign powers it's evident that even secure agencies are not invulnerable to exploitation.
This actually stems from quantum physics: an observation is meaningless on its own... an observer-observation pair is the only valid expression of something. Extend this all the way to government: what is gathered by Dudley Do-Right with the intent of stopping terrorists, and monitoring vulnerable individuals, could easily one day be used to identify political opponents and attack their reputations, and that's just in the cases of domestic use of the intelligence.
If they can get their hands on it, foreign powers with an interest in displacing Canadian business can use this information to manipulate people and markets.
Time for an anecdote: in 2008 I answered my parent's phone to an irate woman who accused me of stealing her son's motorbike. I told her I had no idea what she was talking about. Later on I received a call from the RCMP and they explained that a loading pallet with my parent's phone number imprinted on it was found near the scene of the crime. Turns out the number used to belong to an auction company. I was helpful to the officer and gave them my personal information. 6 years later a buddy of mine ends up in the back of an RCMP cruiser right as I called him - they ran my name and up came "Under investigation for theft." All because I answered my parents' home phone and cooperated with the police, anytime I have an interaction with any law enforcement official, my character is called into question.
It's not a question of whether the libertarians are invoking a slippery slope fallacy because there's nothing fallacious about the interaction between gravity and friction. I equate power-over-others as the "gravity" of human behavior, and social resistance as the "friction," and most of history is wrought with this violent struggle.
It's only a matter of how slippery that slope is and how many branches and safety lines there are before the cliff at the bottom. My contention is that if we start sliding, the one thing that can stop us from the undesirable plunge at the bottom is the SCC and Constitution of Canada, which Harper has demonstrated contempt for.
I simply cannot trust our government with these powers.