the government proposes laws, the bundestag approves of it and the bundespresident signs it. the bundestag is, at times, critical of things but i would have to look up an example. the bundespräsident has forever been a sheep. can't remember anybody doing anything out of order. they get "thrown out" as soon as they even only say sth critical of the political mainstream - see mr. wulf.
anything can happen anytime if they get their ppl in line. opposition is hilarious and bold and simple at most. some say it doesn't even exist. i mean, we have a government constructed of a coalition of opposing forces, the CDU and the SPD, and they're marching the same march. depressing.
anybody telling you some other text book alternative theory is just delusional. there's nothing really better at least with regards to privacy or data protection. it's a laughabke myth spread by the german industry trying to draw profits from snowden. again, depressing.
edit: i forgot one entity viewed by many as one last bastion against unjust laws: our highest court, the bundesverfassungsgericht, the constitutional court. it's regarded very highly so let me demonstrate how those judges work. case in point, data retention law (vorratsdatenspeicherung)
court: "you'd like to save data for 12 months? that's too much."
gov: "ok, 6 months."
court: "that's better. agreed."
bundespräsident: signs law